               NOT FOR PUBLICATION WITHOUT THE
              APPROVAL OF THE APPELLATE DIVISION

                                  SUPERIOR COURT OF NEW JERSEY
                                  APPELLATE DIVISION
                                  DOCKET NO. A-0938-19T3

STATE OF NEW JERSEY,

     Plaintiff-Appellant,              APPROVED FOR PUBLICATION

v.                                               April 20, 2020

                                           APPELLATE DIVISION
DAVID GHIGLIOTTY,

     Defendant-Respondent.
_________________________

           Argued telephonically March 18, 2020 –
           Decided April 20, 2020

           Before Judges Fuentes, Haas and Enright.

           On appeal from an interlocutory order of the Superior
           Court of New Jersey, Law Division, Union County,
           Indictment No. 17-02-0154.

           Michele C. Buckley, Special Deputy Attorney
           General/Acting Assistant Prosecutor, argued the cause
           for appellant (Lyndsay V. Ruotolo, Acting Union
           County Prosecutor, attorney; Michele C. Buckley, of
           counsel and on the brief).

           Elizabeth Cheryl Jarit, Deputy Public Defender,
           argued the cause for respondent (Joseph E. Krakora,
           Public Defender, attorney; Elizabeth Cheryl Jarit, of
           counsel and on the brief).

     The opinion of the court was delivered by
HAAS, J.A.D.

        In this appeal, we address the novel issue of whether a firearms toolmark

identification expert's use of untested three-dimensional (3D) computer

imaging technology known as BULLETTRAX, in conjunction with the

traditional technique of comparing evidence and test bullets using a

comparison microscope, requires that a Frye1 hearing be held to establish the

scientific reliability of the BULLETTRAX machine and related software.

        Following an evidentiary hearing, the trial court concluded that the

State's expert relied upon the BULLETTRAX technology and the images it

produced in concluding that a bullet fragment taken from the murder victim

likely came from a handgun later seized from defendant David Ghigliotty. In

so ruling, the court made extensive factual and credibility findings pertaining

to the expert's testimony about his use of the images, and its findings are

entitled to our deference on appeal. Under these circumstances, we conclude

that the court correctly determined that a Frye hearing was necessary to

demonstrate the reliability of the computer images of the bullets produced by

BULLETTRAX before the expert would be permitted to testify at trial.




1
    Frye v. United States, 293 F. 1013, 1014 (D.C. Cir. 1923).


                                                                         A-0938-19T3
                                        2
                                       I.

      To place this issue in its proper context,2 we begin by providing a

general overview of the field of firearm identification, which "is a specialized

sub-specialty of toolmark identification specifically related to the firearm

mechanism's working surfaces." Thompson at 7-8, 28. In this case, the "tool"

is the firearm.   Thompson at 7; 2009 NRC Report at 150-51.            The tool

surfaces, which include the interior of the firearm barrel, the chamber, and

parts of the action, "can produce toolmarks on fired and unfired ammunition

components." Thompson at 7. Toolmarks are "inherently three-dimensional."

2008 NRC Report at 186.

2
  The necessary contextual background information pertaining to firearm and
toolmark identification presented in this section is primarily taken from four
scientific reports that defendant submitted to the trial court. Portions of the
reports were also cited in the trial court's opinion.

      The four reports, and the citations we will use to refer to them, are as
follows: (1) Robert M. Thompson, Firearm Identification in the Forensic
Science Laboratory (National District Attorneys Association, Alexandria, VA),
2010 (Thompson); (2) National Research Council, Committee to Assess the
Feasibility, Accuracy, and Technical Capability of a National Ballistics
Database, Ballistic Imaging (Nat'l Academies Press, Washington, D.C.), 2008
(2008 NRC Report); (3) National Research Council, Committee on Identifying
the Needs of the Forensic Science Community, Strengthening Forensic Science
in the United States: A Path Forward (Nat'l Academies Press, Washington,
D.C.), 2009 (2009 NRC Report); and (4) President's Council of Advisors on
Science and Technology, Report to the President, Forensic Science in Criminal
Courts: Ensuring Scientific Validity of Feature-Comparison Methods
(Executive Office of the President), September 2016 (PCAST Report).



                                                                        A-0938-19T3
                                       3
      Toolmark evidence may consist of "class characteristics," which are not

unique,   and   "individual   characteristics,"   which   are   "microscopically

dissimilar." Thompson at 8-10. "Class characteristics" are firearm features

"shared by many items of the same type" and determined by the manufacturer

that "help narrow the population of potential firearm sources" when doing an

identification. Thompson at 8; 2009 NRC Report at 152. They include "the

size of the cartridge chambered by the firearm, the orientation of the extractor

and ejector, and the number, width, and twist direction of the land and grooves

of the barrel rifling." Thompson at 8, 15; 2009 NRC Report at 152.

      In contrast, "individual characteristics" of a firearm are "fine

microscopic markings and textures" that "are random in nature, usually arising

from the tool working surface incidental to manufacture, but can also be the

result of use, wear, and possible care and/or abuse of the tool," and that form

striated or impressed toolmarks on ammunition. Thompson at 9-11; 2009 NRC

Report at 152.       Because of their uniqueness, a firearm's individual

characteristics make firearm identification possible, so long as the toolmarks

imparted are "reproducible for comparisons." Thompson at 7-9.

      "For the science of toolmark identification, the underlying hypothesis is

that a toolmark can be identified to a specific tool that produced it, to the

practical exclusion of all other tools." Thompson at 9-10; 2009 NRC Report at



                                                                        A-0938-19T3
                                        4
150. Although it is impossible to prove the hypothesis "by testing all tools

ever produced in the world," firearms examiners make identifications "based

on observation and experimentation" which includes the consideration of

"known non-match" toolmark comparisons.        Thompson at 10; 2009 NRC

Report at 152.

      The science of firearm and toolmark identification is well-established,

spanning over 100 years in the United States. Thompson at 8. "There is a

foundation of knowledge about firearm and toolmark identification that has

been organized over time and is described in forensic textbooks, scientific

literature, reference material, training manuals, and peer reviewed scientific

journals." Thompson at 28-29. The Association of Firearm and Toolmark

Examiners (AFTE), an international body of practitioners, is the largest

professional organization in the field and publishes a professional journal

concerning firearm and toolmark science. Thompson at 11, 29.

      Neither the underlying principles nor the methodology has changed

significantly during the last 100 years. Thompson at 8. The AFTE recognizes

that the "most widely accepted method used in conducting a toolmark

examination is a side-by-side, microscopic comparison of the markings on a

questioned material item to known source marks imparted by a tool." PCAST

Report 104. A firearms toolmark examiner uses a comparison microscope to



                                                                      A-0938-19T3
                                      5
compare toolmarks on an evidence bullet with toolmarks present on a test fired

bullet from the suspected weapon that is linked to either the crime scene or a

suspect.   Thompson at 10, 27.      Class characteristics are evaluated first,

followed by individual characteristics. Thompson at 26; 2009 NRC Report at

152; PCAST Report at 11, 104.

      The design of the comparison microscope, the primary tool used by

firearms toolmark examiners, has not changed in approximately eighty years.

Thompson at 8. It consists of two compound microscopes that are joined

together, "giving the examiner the ability to observe and compare two objects

at the same time under magnification."        Ibid.   While the comparison

microscope is considered "an absolutely necessary instrument" in making "the

identification of toolmarks on fired bullets," both Thompson's article and the

2009 NRC Report note that examiners "might use other complimentary

microscopic and photographic instrumentation." Thompson at 8; 2009 NRC

Report at 153.

      When an examiner finds that the toolmarks on an evidence bullet and a

test bullet fired from the suspected weapon are in "sufficient agreement," a

firearm identification can be made.    Thompson at 9-10, 26.      "[T]he final

determination of a match is always done through direct physical comparison of




                                                                      A-0938-19T3
                                      6
the evidence by a firearms examiner, not the computer analysis of i mages."

2009 NRC Report at 153.

      In 1992, the AFTE adopted a "Theory of Identification" and standardized

the terms and conclusions that firearms examiners should use to describe

examination results.   Thompson at 11.     Revised in 2011, the Theory of

Identification recognizes that identification is "subjective in nature" and

defines and explains the "sufficient agreement" standard used by examiners:

            1. The theory of identification as it pertains to the
            comparison of toolmarks enables opinions of common
            origins to be made when the unique surface contours
            of two toolmarks are in "sufficient agreement."

            2. This "sufficient agreement" is related to the
            significant duplication of random toolmarks as
            evidenced by a pattern or combination of patterns of
            surface contours. Significance is determined by the
            comparative examination of two or more sets of
            surface contour patterns comprised of individual
            peaks, ridges and furrows. Specifically, the relative
            height or depth, width, curvature and spatial
            relationship of the individual peaks, ridges and
            furrows within one set of surface contours are defined
            and compared to the corresponding features in the
            second set of surface contours.        Agreement is
            significant when the agreement in individual
            characteristics   exceeds     the   best    agreement
            demonstrated between toolmarks known to have been
            produced by different tools and is consistent with
            agreement demonstrated by toolmarks known to have
            been produced by the same tool. The statement that
            "sufficient agreement" exists between two toolmarks
            means that the agreement of individual characteristics
            is of a quantity and quality that the likelihood of

                                                                      A-0938-19T3
                                      7
            another tool making the mark is so remote as to be
            considered a practical impossibility.

            3. Currently the interpretation of individualization/
            identification is subjective in nature, founded on
            scientific principles and based on the examiner's
            training and experience.

            [Theory of Identification as it Relates to Toolmarks:
            Revised, 43 AFTE J. 287 (2011) (emphasis added).]

      Based on its Theory of Identification, the AFTE developed four potential

conclusions for examiners to make following an investigation:                  (1)

identification; (2) inconclusive; (3) elimination; and (4) unsuitable, meaning

that the evidence was not suited for examination. Thompson at 11-12.

      An "identification" is "[a]greement of a combination of individual

characteristics and all discernible class characteristics where the extent of

agreement exceeds that which can occur in the comparison of toolmarks made

by different tools and is consistent with the agreement demonstrated by

toolmarks known to have been produced by the same tool." Thompson at 11.

      A finding of "inconclusive" results when there exists:         (1) "[s]ome

agreement of individual characteristics and all discernible class characteristics,

but insufficient for an identification"; or (2) "[a]greement of all discernible

class characteristics without agreement or disagreement of individual

characteristics due to an absence, insufficiency, or lack of reproducibility"; or

(3) "[a]greement of all discernible class characteristics and disagreement of

                                                                         A-0938-19T3
                                        8
individual characteristics, but insufficient for an elimination." Id. at 11-12. A

finding of "elimination" means that there exists "[s]ignificant disagreement of

discernible class characteristics and/or individual characteristics." Id. at 12.

        As of 2010, the error rate in actual casework had not been studied or

determined. Id. at 29. However, "reviews of proficiency testing data show

that the error rate for misidentifications for firearm evidence is approximately

1.0%, and for toolmark evidence it is approximately 1.3%."              Ibid.      An

individual examiner's error rate should be considered in each case. Ibid.

                                        II.

        With this essential background in mind, we now turn to the facts of the

present case. On June 22, 2004, the body of the victim, Taji Pile, was found

on the side of the road with a bullet wound to the head. The police did not

recover a murder weapon at the scene, but were able to retrieve three bullets

from the victim's body.

        During the investigation that followed, the police interviewed defendant,

who was "a close friend" of the victim. Defendant stated he and the victim had

used and sold marijuana together in the past, and that he last saw the victim on

the day he was killed. The police did not arrest or charge defendant at that

time.




                                                                          A-0938-19T3
                                         9
      On May 5, 2005, the police arrested defendant for unlawful possession

of a handgun. The investigation revealed that the handgun had been purchased

by the victim's brother in October 2003. Defendant was later convicted of the

handgun charge.

      Detective Gary Mayer, a firearms expert at the Union County

Prosecutor's Office, was responsible for conducting a firearm identification

test involving the three bullets found at the murder scene and the handgun

seized from defendant. Only one of the projectiles recovered at the murder

scene, a bullet jacket fragment that was "significantly damaged, was deemed

intact enough to be suitable for comparison."

      Using only a standard comparison microscope, Mayer compared the

jacket fragment with test shots fired from the handgun.      His comparison

yielded "negative results" or "an elimination."

      In 2015, more than ten years after the victim's murder, the prosecutor's

office reopened its investigation. The detective assigned to the case asked

Lieutenant Michael Sandford, who was assigned to the Union County Police

Department's Firearms Identification Unit, 3 to help him "understand why

[Mayer's] original opinion . . . was a negative [or an elimination]." Sandford


3
  Sandford had thirty-three years of experience in the Firearms Identification
Unit, and had testified as an expert in court approximately eighty-five times.


                                                                      A-0938-19T3
                                       10
twice told the detective that as a matter of standard practice, "we don't re-

examine [what] another [firearms] examiner had examined," but "[a]fter

maybe the third time" the detective asked for help, Sandford agreed to conduct

the re-examination.

      Toward that end, in 2016, Sandford completed a "bullet identification"

on the ballistic evidence, or a study to determine whether a projectile is "a

component or a bullet."      Sandford determined that two of the recovered

projectiles were "lead core . . . from a bullet" that could not be used to conduct

a microscopic toolmark comparison.          The third projectile, however, was a

"heavily damaged [bullet] jacket" that could be used for a microscopic

toolmark comparison. Sandford was unable to determine what company had

manufactured the bullet jacket.

      Following the bullet identification study, Sandford conducted a

microscopic comparison of the bullet jacket, Mayer's test shots, and test shots

of his own, using a comparison microscope. He testified that the comparison

microscope enabled him "to observe two components or two pieces of

evidence side by side under a singular binocular eyepiece under the same

lighting, magnification and orientation."

      Initially, Sandford was "unable to come to a conclusive result" and

therefore "couldn't support [Mayer's] opinion." He decided that he needed to



                                                                         A-0938-19T3
                                       11
examine the evidence "further" in order to "come to an opinion of [his] own."

Thereafter, Sandford took approximately ten additional test shots, usin g

ammunition from several different manufacturers because, in his experience,

"a firearm would mark differently with different ammunition."        He then

compared the new test shots with the jacket fragment, and he also compared

the new test shots with his prior test shots and Mayer's test shots, reviewing

the evidence "many" times. Sandford testified that even with this additional

work with the comparison microscope, he still could not reach a conclusion on

the question of whether the fragment could have come from defendant's

handgun.

      In June 2016, Sandford and another firearms identification examiner

from his unit, Sergeant Krzysztof Audinis, attended a training seminar in New

Orleans led by Andrew Boyle, the firearms reference manager at Ultra

Electronics Forensic Technology, Inc. (UEFT). Boyle's position was in the

sales and marketing group, and he presented workshops and demonstrations

related to the BULLETTRAX 4 machine and its software component,

Matchpoint.



4
  At times, the trial court referred to BULLETTRAX as "BULLETRAX" or
"BULLETRAX HD3D."              However, the manufacturer's website uses
BULLETTRAX as the nomenclature for the machine and we do so herein. See


                                                                      A-0938-19T3
                                     12
       Boyle was well-versed in how BULLETTRAX 5 worked from a user

perspective, but he did not have a computer science background and was not a

firearms examiner.     Because this technology was developed by UEFT's

computer programmers and software engineers, Boyle was not familiar with

the specific algorithms 6 and computer programming involved with the

technology.

       Boyle explained that BULLETTRAX uses computer automation and

confocal microscopy to scan the surface of a bullet, read its topography in 3D,

and create 2D and 3D images of a bullet's surface. If the subject bullet is

damaged, the operator can program the machine to scan only portions of the

bullet.   After the operator manually positions the bullet, sets the scanning

parameters, and presses the start button, the machine operates by itself.

       The bullet's surface, rotated by a motor, is scanned with a confocal lens

and the machine automatically makes adjustments to ensure optimal, consistent

https://www.ultra-forensictechnology.com/en/our-products/ballistic-
identification/bullettrax/ (accessed Mar. 23, 2020).
5
    UEFT developed the BULLETTRAX machine in 2003.
6
   Sandford testified that BULLETTRAX used an algorithm as part of the
image acquisition process that "creates . . . a digital representation or a
numeric representation of what it sees under the microscope." However, he
did not know who created the algorithm, how it was developed, or how many
versions had been developed. He said he "didn't have much interest in the
algorithm," and admitted that he did not "fully understand" it.


                                                                            A-0938-19T3
                                       13
lighting and focus.   According to Boyle, the scanner's capture area is 1.6

millimeters, meaning that small sections of the bullet are scanned and then

"stitched" together, using an algorithm, into a single image. Acquisition of the

image of a damaged bullet takes, on average, twenty to twenty-five minutes.

      Once bullet images are acquired via BULLETTRAX, the images are

viewed using Matchpoint, a software program.             According to Boyle,

Matchpoint's features are "designed to complement the workflow that [the

examiners] are accustomed to" and allows them to emulate how a visual

analysis using a comparison microscope would work, with certain advantag es.

      For example, Boyle testified that the examiner can compare up to six

images at one time on a single screen as opposed to a single pair and switch

back and forth between 2D and 3D views. The images of the bullet's surface

can be viewed across a flat plane, with consistent lighting and focus applied to

each, allowing the examiner to "have a bird's-eye view of not just one little

area, like they would typically have on a comparison microscope."             An

examiner can reposition the images, manipulate the lighting, brightness,

contrast and apply those changes instantaneously across all images, whereas

such adjustments must be made manually when using a comparison

microscope.




                                                                        A-0938-19T3
                                      14
      Boyle testified that following his 2016 AFTE workshop, at which he

"show[ed] what we can do with bullet comparisons," Sandford reached out to

the company's sales director and "made arrangements to visit [UEFT's office

in] Montreal to have exhibits imaged into our system." Sandford explained

that the use of BULLETTRAX and Matchpoint for the Pile investigation

appealed to him because he "was looking . . . for tools that would help [him]

be more efficient in [his] examination" of the evidence. He testified that "a

microscopic comparison on . . . damaged projectiles is a very cumbersome

examination" and he "felt that [he] needed some other tool to help [him] to

complete this examination . . . in a reasonable amount of time." Sandford

noted the need to position the projectiles to ensure that "the area of interest

that you're looking at [is] top-dead center" on both projectiles, which requires

constant manual manipulation of the angles, lighting, and magnification.

      Subsequently, Sandford brought the physical evidence to Montreal, and

used the Matchpoint software to view images of the evidence created by

BULLETTRAX.7 Boyle operated the BULLETTRAX machine and acquired

3D, black-and-white images of the surface of the damaged bullet jacket and

four test shots. Thus, Boyle was responsible for positioning the projectiles


7
  This was the first and only time Sandford had ever used BULLETTRAX in
conducting a firearms identification study.


                                                                        A-0938-19T3
                                      15
into the machine, adjusting the brightness, and operating the computer

program associated with it.

      Thereafter, Sandford looked at the images side-by-side on a computer

screen using Matchpoint "to try and target areas of interest to determine . . . if

[he] was going to go back and continue with further microscopic comparisons

or not." He compared the bullet jacket to each of the four test shots. He also

looked at one of Mayer's test shots. Boyle showed Sandford how to use the

Matchpoint software, which included tools for flattening and manipulating the

images, adjusting the brightness, zooming in, and "different overlays of . . .

color scaling."

      During this process, Sandford identified five areas of interest, which he

described as "four [LEAs] and . . . a G[EA] area on the . . . evidence item."

According to Sandford, a "LEA" is "[a] land engraved impression in rifling on

a projectile" and a "GEA" is "[a] groove engraved area."

      Audinis accompanied Sandford to Montreal and while Sandford was

working on Matchpoint, he communicated his findings to Audinis, who

attempted to locate the areas of interest on the physical evidence using a

comparison microscope. The partners remained in Montreal for three days,

from June 20 through June 22, 2016.




                                                                         A-0938-19T3
                                       16
      Sandford     explained     that   acquisition    of   the    images    through

BULLETTRAX, which utilizes confocal microscopy, was advantageous

"because [BULLETTRAX] takes away the influence of color when looking at

[the] images" while "[a] comparison microscope . . . uses color and color can

influence you in different ways." Sandford testified that he incorporated some

of the grayscale images from BULLETTRAX, in the form of "screen shots,"

into his subsequent written report to the prosecutor's office, although he

asserted that he did not "make any conclusions" based on the BULLETTRAX

images. Sandford placed markings on the screen shots when he came back to

the lab to highlight the areas of interest he wanted to explore under t he

microscope.

      When Sandford returned to his lab, he "waited a couple [of] weeks to

clear [his] mind" before looking at the evidence again. Eventually, he used the

screen shots from BULLETTRAX "like[] a GPS" to guide his comparison

microscope analysis of the "areas of interest" and "came to an opinion of an

identification or a positive identification."

      More specifically, Sandford explained that he "found sufficient

agreement in four different [LEAs] and a G[EA] . . . between the evidence and

a test shot." He testified that his positive identification of the bullet, as one that

was likely shot from defendant's gun, was grounded in his "training and



                                                                             A-0938-19T3
                                         17
experience and education as a practitioner in firearms identification" and his

handling of over 2300 cases. 8 Although Sandford was not able to make a

positive identification prior to using the BULLETTRAX technology, he

testified that all of the conclusions and opinions he rendered were based on his

"live comparison on a comparison microscope" as opposed to "photographs or

a computer image."

      Sandford    further   explained   that   his   use   of   Matchpoint   and

BULLETTRAX helped him "define areas that [he] wanted to look at closer"

and "[t]o avoid . . . the cumbersome task of [manually] going around the entire

circumference of a damaged bullet" as he "wanted to do [the examination]

more efficiently." He said that not all of the areas of interest he flagged using

BULLETTRAX led to a finding of sufficient agreement under the comparison

microscope, and that, conversely, he had found areas of sufficient agreement

that he "did not see in Montreal." Thus, Sandford asserted that even had he

not used BULLETTRAX and Matchpoint to assist him, he "would have found



8
    Sandford testified that Audinis conducted a peer review, meaning an
independent examination of the evidence, after he made his identification in
the lab based upon his "microscopic comparison work only." Sandford
acknowledged that a peer reviewer "is not supposed to be involved" in the
initial examination at all or have any information about the first examiner's
conclusion. However, he stated that Audinis worked with him on the case
because they were a "small lab" of only two examiners.


                                                                        A-0938-19T3
                                        18
those same areas of interest and identification points" anyway using the

comparison microscope "if [he] kept at it and continued [his] investigation."

      Nevertheless, Sandford acknowledged that the BULLETTRAX images

served as a guide, helped him "move forward" with his examination of the

evidence, and that he "relied on . . . what [he] observed in . . . Montreal to look

at specific areas or certain areas . . . rather than going through the entire

circumference of the evidence." He said that there was "no way to put a time

frame" on how long an investigation using a comparison microscope might

take as it varied case to case.

      With regard to Sandford's claim that the BULLETTRAX technology did

not affect his subsequent positive identification, defense counsel asked him

about an email exchange with a UEFT employee, Stacy Stern, while Sandford

was still in Montreal.     Stern wrote to Sandford:     "I heard things may be

looking good?" Sandford replied: "They just stepped over from looking good

to outstanding." Sandford testified that his use of the word "outstanding" in the

email meant "that the intent of what we went there for, we achieved that intent.

To identify the areas [of interest] that we wanted to look at."

      Sandford did not discuss the possibility of image distortion with Boyle

but admitted that "it could have" affected how he located areas of interest. In

this regard, Boyle testified that "one of the drawbacks" of using confocal



                                                                          A-0938-19T3
                                        19
microscopy in BULLETTRAX "is that it has a difficult time capturing

information from especially steep slopes" and "deals better with . . . a more

stable shaped surface." This means that if there are areas with "especially

steep slopes" on a bullet surface, then the computer-generated image could

have "areas of missing data" that would appear as a "black region."

      Boyle also stated that acquisition issues can result if a bullet surface is

too shiny or too dark, and artificial "noise" (markings not actually present on

the bullet) can show up in the image. He did not recall any steep slope issues

or other distortion problems with the images acquired in this case. Boyle said

that he was not aware of any validation studies done on BULLETTRAX

concerning image acquisition or image viewing.

      Sandford kept in touch with Boyle after his trip to Montreal and gave a

presentation at the following year's AFTE training conference with him.

Sandford admitted that he discussed the Pile case during his pres entation and

that a printed "summary of that training" mentioned "how 3D comparison . . .

recently led to a conclusive result in a decade-old cold case homicide." Boyle

testified that the seminar "showcase[d] the benefits of how 3D analysis helped

them work the case material" and "images were shown in regards to how the

machine aided them in pinpointing areas of interest to explore on the

comparison microscope."



                                                                        A-0938-19T3
                                       20
                                     III.

      Based upon Sandford's positive identification of the bullet fragment as a

projectile that had been shot from the gun seized from defendant in 2005, a

grand jury indicted defendant on March 1, 2017 for the first-degree murder of

Taji Pile, second-degree unlawful possession of a handgun, and second-degree

unlawful possession of a firearm.

      On April 5, 2018, defendant moved to preclude or limit Sandford's

proposed expert testimony pursuant to Frye. The court scheduled a N.J.R.E.

104 hearing and ordered the State to produce "any and all manuals, policies or

procedures from [UEFT]" for the BULLETTRAX software. UEFT refused to

provide this information to the State and, therefore, it was unable to comply

with the court's order.

      The court thereafter conducted a three-day evidentiary hearing at which

Sandford and Boyle testified as discussed above. At the conclusion of the

hearing, the court rendered a lengthy written opinion and order granting

defendant's motion for a Frye hearing to determine the reliability of the

BULLETTRAX machine and the Matchpoint software. Before discussing that

ruling in greater detail, we briefly summarize the legal principles governing

the issue presented.




                                                                       A-0938-19T3
                                      21
      "[T]he Judiciary must ensure that proceedings are fair to both the

accused and the victim.      Trial judges partly fulfill that responsibility by

serving as a gatekeeper.      In that role, they must assess whether expert

testimony is sufficiently reliable before it can be presented to a jury." State v.

J.L.G., 234 N.J. 265, 307-08 (2018). "While juries would not always accord

excessive weight to unreliable expert testimony, there is substantial danger that

they would do so, precisely because the evidence is labeled 'scientific' and

'expert.'" State v. Cavallo, 88 N.J. 508, 518 (1982).

      Pursuant to N.J.R.E. 702, "[i]f scientific . . . knowledge will assist the

trier of fact to understand the evidence or to determine a fact in issue, a

witness qualified as an expert by knowledge, skill, experience, training, or

education may testify thereto in the form of an opinion or otherwise." To meet

this requirement,

            the proponent of expert evidence must establish three
            things: (1) the subject matter of the testimony must be
            "beyond the ken of the average juror"; (2) the field of
            inquiry "must be at a state of the art such that an
            expert's testimony could be sufficiently reliable"; and
            (3) "the witness must have sufficient expertise to offer
            the" testimony.

            [J.L.G., 234 N.J. at 280 (quoting State v. Kelly, 97
            N.J. 178, 208 (1984)).]

      The three prongs cited above "are construed liberally in light of Rule

702's tilt in favor of the admissibility of expert testimony." State v. Jenewicz,

                                                                         A-0938-19T3
                                       22
193 N.J. 440, 454 (2008). At issue in this case is the second prong concerning

reliability of the field of inquiry. "In criminal cases, [our Supreme] Court has

continued to rely on the Frye standard to assess reliability." J.L.G., 234 N.J. at

280; accord State v. Harvey, 151 N.J. 117, 170 (1997); State v. Torres, 183

N.J. 554, 568 (2005). 9

      In Frye, 293 F. at 1014, the District of Columbia Court of Appeals

explained:

             Just when a scientific principle or discovery crosses
             the line between the experimental and demonstrable
             stages is difficult to define. Somewhere in this
             twilight zone the evidential force of the principle must
             be recognized, and while courts will go a long way in
             admitting expert testimony deduced from a well-
             recognized scientific principle or discovery, the thing
             from which the deduction is made must be sufficiently
             established to have gained general acceptance in the
             particular field in which it belongs.

      The Frye test "requires trial judges to determine whether the science

underlying the proposed expert testimony has 'gained general acceptance in the


9
   In In re Accutane Litigation, 234 N.J. 340, 347-48, 398-99 (2018), the
Supreme Court adopted the factors identified in Daubert v. Merrell Dow
Pharm., Inc., 509 U.S. 579, 592-93 (1993), which describe a methodology-
based approach for determining scientific reliability, to "aid our trial courts in
their role as the gatekeeper of scientific expert testimony in civil cases," but
explicitly "retain[ed] the general acceptance test for reliability [as established
in Frye,] in criminal matters." See also State v. Cassidy, 235 N.J. 482, 492
(2018) (noting that the Court has "not altered [its] adherence to the [Frye]
general acceptance test for reliability in criminal matters").


                                                                         A-0938-19T3
                                       23
particular field in which it belongs.'" J.L.G., 234 N.J. at 280 (quoting Frye,

293 F. at 1014). "[T]here are three ways to establish general acceptance under

Frye: expert testimony, authoritative scientific and legal writings, and judicial

opinions." J.L.G., 234 N.J. at 281. "Proof of general acceptance does not

mean that there must be complete agreement in the scientific community abo ut

the techniques, methodology, or procedures that underlie the scientific

evidence." State v. Chun, 194 N.J. 54, 91-92 (2008); accord State v. McGuire,

419 N.J. Super. 88, 133 (App. Div. 2011).

      "[T]ool mark analysis is not a newcomer to the courtroom." McGuire,

419 N.J. Super. at 130. "Testimony by tool mark experts has been admitted in

New Jersey courts [under the Frye standard] without objection" and also "in

other jurisdictions." Id. at 130-31; see State v. Behn, 375 N.J. Super. 409,

416-19 (App. Div. 2005) (discussing admitted testimony from "a ballistics and

tool mark identification expert" linking bullets recovered from victim to a rifle

that the defendant had purchased); State v. Cito, 213 N.J. Super. 296, 299

(App. Div. 1986) (discussing admitted testimony from a toolmark expert

linking a screwdriver seized from the defendant's home to the scene of the

crime).




                                                                         A-0938-19T3
                                       24
                                      IV.

      Here, the trial court's concern was not with the general acceptance of the

discipline of firearm toolmark identification, but rather with the new technique

Sandford employed in reaching his conclusion. After making extensive factual

findings pertaining to the testimony and the relevant scientific studies, it held

"that it need not hold a Frye hearing to determine the general acceptance of

toolmark identification."     However, it conditioned the admissibility of

Sandford's expert testimony upon a finding that BULLETTRAX and

Matchpoint were scientifically reliable and held that a Frye hearing was

warranted for that purpose.

      While the court credited Sandford's testimony "that [BULLETTRAX]

provided assistance in identifying areas of interest on the evidence bullet" and

served as "a shortcut to save time in conducting the same review he otherwise

would have made manually over the entire circumference of the evidence

bullet and comparison bullets," it discredited Sandford's testimony that

BULLETTRAX "did not inform his ultimate opinion in this matter ." Instead,

it found that "the [BULLETTRAX] images . . . at least partially formed the

basis of [Sandford's] opinion that the evidence bullet and the test fired shot in

this case were a match" and were "so intertwined" with his "subsequent




                                                                         A-0938-19T3
                                       25
laboratory comparisons" that they "cannot be separated from his later

identification simply because time passed."

      Thus, the court found "that the images created by [BULLETTRAX] were

an integral part of . . . Sandford's opinion" that the bullet fragment came from

defendant's gun. The court noted that Sandford testified that "h e used the

screenshots of the images he viewed on Matchpoint as a 'GPS' in order to

readily identify the areas of the evidence bullet that he believed were 'of

interest' when he examined the bullet under his confocal microscope back in

New Jersey."

The court continued:

            This [c]ourt is therefore unassuaged by . . . Sandford's
            testimony that he could have made the identification
            without the use of [BULLETTRAX] because, stated
            simply, that is not what occurred here and to say that
            the identification was inevitable is purely speculative.
            This assertion is also contradicted by the findings of
            the original toolmark examiner [Mayer] who excluded
            the firearm in this case as a possible source of the
            evidence bullet.

      The court also cited Sandford's email exchange with Stern while in

Montreal in which he wrote that due to his use of BULLETTRAX, the

situation "stepped over from looking good to outstanding," and found that his

statement "call[ed] into question [his] claim that he never had an 'ah-ha'

moment or a point in time where he thought there would probably be an



                                                                        A-0938-19T3
                                      26
identification while using" BULLETTRAX. It further found that Sandford's

testimony that the images did not inform his ultimate opinion was "even more

difficult to reconcile" since "Audinis . . . was using a comparison microscope

in the same room as . . . Sandford, as he directed him to examine certain areas

of the evidence bullet."

      In addition, the court cited Sandford's joint presentation with Boyle at

the 2017 AFTE conference "on how new 3-D comparison tools led to a

conclusive identification in a decade-old cold case" as further evidence that,

despite his assertions to the contrary, the BULLETTRAX technology Sandford

used in Montreal clearly influenced his later conclusion that the bullet

fragment was shot from defendant's gun.

      As to the admissibility of evidence concerning this new technology in

the absence of a Frye hearing, the court found, based upon Boyle's credible

testimony, that BULLETTRAX "is a highly automated technology that does

not merely photograph the bullet's surface, as suggested by the State, but

instead digitally recreates the entire surface area." It also cited the fact that it

"was unable to find—and the parties did not present—any published or

unpublished decisions addressing the reliability or general acceptance of

[BULLETTRAX] in connection with the examination and identification of

ballistics."



                                                                           A-0938-19T3
                                        27
      As to the Matchpoint software, the court found that its reliability was

"[e]qually unproven at this time."       It added that the record lacked "any

validation     studies   or   indeed   any   records   concerning   the    testing

[BULLETTRAX] has undergone to determine the accuracy and reliability of

the images it produces [and/or] the [Matchpoint] software that permits

examiner interaction with those images."

      Accordingly, the court ordered that because Sandford relied upon the

untested BULLETTRAX technology in reaching his positive identification of

the bullet fragment, a Frye hearing was needed to determine the scientific

reliability of his proposed testimony concerning this device.

      The court also addressed two other issues raised by defendant. First,

defendant again demanded that the State provide him with the BULLETTRAX

algorithms in advance of the Frye hearing. In support of this request, however,

defendant relied solely upon defense counsel's request for this information, and

did not submit a certification from its expert detailing the reasons why the

production of the algorithms was necessary, or what other specific discovery

concerning BULLETTRAX and Matchpoint might be warranted.

      Nevertheless, citing Chun, 194 N.J. at 69-70, the court again found that

production of the algorithms was necessary to ensure "defendant's right to a

fair trial."   Without citing anything else, the court found that the Sta te's



                                                                          A-0938-19T3
                                        28
provision of this information would allow "the defense . . . to effectively cross

examine the State's witnesses at trial and to prepare for the Frye hearing" since

"[t]he review and testing of algorithms and/or source coding utilized in a new

or untested technology is required in order to determine its reliability." While

the court stated it was amenable to making the production of the algorithms

subject to a protective order, the terms of such an order were not delineated by

the court or the parties.

      Finally, defendant argued that if the BULLETTRAX technology

ultimately passed the Frye test, Sandford should not be permitted to testify that

he had come to his conclusion concerning the bullet fragment to a reasonable

degree of scientific certainty.     Instead, defendant asked that Sandford's

testimony be limited to his claim that the evidence bullet was consistent with

having been fired from the gun recovered from defendant, but not to the

exclusion of all other guns. After examining the studies discussed earlier in

this opinion and caselaw from other jurisdictions, the court granted this request

even though if BULLETTRAX did not survive Frye scrutiny, the court's order

limiting Sandford's expert testimony would be moot.

                                       V.

      We subsequently granted the State's motion for leave to appeal. On

appeal, the State argues that the trial court erred by concluding that Sandford



                                                                        A-0938-19T3
                                       29
relied upon the BULLETTRAX technology in arriving at his conclusion that

the bullet fragment came from defendant's gun. It alleges that Sandford denied

basing his findings on what he observed in Montreal on the BULLETTRAX

machine and, instead, his "ultimate results and conclusions" were made using

only a standard comparison microscope. Therefore, the State claims that a

Frye hearing concerning BULLETTRAX and Matchpoint was not necessary.

We reject these contentions because the court's contrary determinations were

squarely based upon its judgment that Sandford's testimony on this point was

not credible.

      "[W]hen the result of the contest must turn on the truthfulness of

witnesses, the superior advantage of the trial judge in seeing and hearing and

appraising the disputants must ordinarily be regarded as the fulcrum on which

the issue should be resolved." Abeles v. Adams Eng'g Co., 35 N.J. 411, 423-

24 (1961). For this reason, appellate "[c]ourts generally defer to a trial court's

credibility findings about the testimony of expert witnesses[]" and "accept the

court's factual 'findings to the extent that they are supported by substantial

credible evidence in the record[.]'" J.L.G., 234 N.J. at 301 (quoting Chun, 194

N.J. at 93).

      Thus, "[a]n appellate court should not disturb the trial court's findings

merely because 'it might have reached a different conclusion were it the trial



                                                                         A-0938-19T3
                                       30
tribunal' or because 'the trial court decided all evidence or inference conflicts

in favor of one side' in a close case." State v. Elders, 192 N.J. 224, 244 (2007)

(quoting State v. Johnson, 42 N.J. 146, 162 (1964)). Accordingly, "[a] trial

court's findings should be disturbed only if they are so clearly mistaken 'that

the interests of justice demand intervention and correction.'" Ibid. (quoting

Johnson, 42 N.J. at 162).

      Applying this standard, we are satisfied that the trial court's factual

findings and credibility determinations are fully supported by substantial

credible evidence and, as such, are unassailable on appeal. The record makes

clear that the BULLETTRAX images, which Sandford reviewed both while in

Montreal and back in his lab in New Jersey, prompted him to reexamine the

physical evidence under the comparison microscope. He even testified that he

included some of the images in his report to the prosecutor's office. After

reviewing the images and reexamining the evidence, he changed his ultimate

conclusion from "inconclusive" to an "identification."      In that regard, the

BULLETTRAX images clearly aided and influenced the course of his

investigation and informed his ultimate opinion, as the trial court properly

found.

      In reaching this conclusion, the court considered Sandford's repeated

assertion that he was able to put aside everything he learned from examining



                                                                        A-0938-19T3
                                       31
the bullet fragment and the test bullets with the BULLETTRAX machine.

However, the court rejected this claim based on its assessment of Sandford's

credibility on the stand, coupled with the substantive evidence in the record

that firmly demonstrated that the improved images Sandford obtained from the

new technology clearly colored his final conclusion.

      In this regard, it is important to recall that toolmark identification, while

"founded on scientific principles," is "subjective in nature, . . . and based on

the examiner's training and experience." Theory of Identification, 43 AFTE J.

at 287. Here, Sandford had previously been unable to make a finding on the

comparability of the bullet fragment taken from the victim and the test bullets

fired from defendant's gun. His predecessor, Mayer, had already reached a

negative conclusion. It was only after Sandford had the opportunity to use the

new BULLETTRAX technology that he was able to change his determination

from inconclusive to positive.

      The State claims that the trial court should have accepted Sandford's

explanation that the BULLETTRAX merely provided him with "areas of

interest" that he could later examine with the comparison microscope. But,

this begs the question. With unlimited time to examine the bullet fragment and

the test bullets using the microscope, Sandford admitted he could not reach a

definitive conclusion before going to Montreal.          It was only after the



                                                                          A-0938-19T3
                                        32
BULLETTRAX machine guided his analysis that the State's expert was able to

find the areas of the evidence that ultimately led him to change his original

findings.     Under these circumstances, we are satisfied that the trial court

properly rejected the State's argument that the BULLETTRAX technology

played no role in Sandford's final opinion.

         The trial court also pointed to other facts in the record that supported its

determination that Sandford would not have been able to reach his conclusions

if he had not had access to BULLETTRAX. For example, Sandford responded

to an email sent by a UEFT employee by stating that his work on the evidence

had gone "from looking good to outstanding" after he was able to use the new

technology. Sandford later gave a seminar on BULLETTRAX that described

how using the machine "led to a conclusive identification in a decade-old cold

case."      In addition, the court noted that it was "even more difficult to

reconcile" Sandford's claim that he did not rely on BULLETTRAX to reach his

conclusion because his partner, Audinis, was in Montreal at the same time

using a comparison microscope to examine the evidence bullet as Sandford

used the computer images as "a GPS" to guide him.

         In sum, we discern no basis for disturbing the trial court's determination

that BULLETTRAX "play[ed] a fundamental role in the ballistics examination

in this case" and, like that court, we cannot "accept as plausible the assertion



                                                                            A-0938-19T3
                                          33
that [BULLETTRAX] did not form at least a partial basis for . . . Sandford's

ultimate conclusion."

      In so ruling, we reject the State's reliance upon this court's decision in

McGuire in support of its contention that Sandford made an independent

evaluation of the evidence by examining it with a standard comparison

microscope after employing BULLETTRAX and, therefore, his use of the new

technology should be disregarded. In McGuire, a toolmark expert was called

upon to opine whether a plastic garbage bag similar to one found in the

defendant's apartment might have been used in connection with the murder of

her husband. 419 N.J. Super. at 119, 124, 127-30. After examining the bags,

the expert visited the plastic bag manufacturing plant, where he spoke with a

plastics engineer who advised him that a distinctive "cliff" in the bag "could be

caused by an operator putting one of the cutting blades in backwards." Id. at

128-29. The expert then personally examined the tool that cut the bags and

observed how a blade might be replaced backwards. Id. at 133. Ultimately,

the expert "concluded that the 'cliffs' in the bags in this case were likely caused

by a backwards blade."      Ibid.   His conclusion was based, in part, on his

conversation with the plastics engineer. Id. at 129.

      On appeal, the defendant argued that the expert's opinion concerning the

"'cliffs' on [the] edges of the bags was inadmissible hearsay from an



                                                                          A-0938-19T3
                                        34
unidentified person and not a valid basis for expert testimony." Id. at 133. We

disagreed, concluding that the expert had "formulated his own opinion" about

the "cliffs." Ibid. It held that "[t]here is nothing improper about an expert

obtaining information from an outside source, as long as the expert makes an

independent evaluation of the information and is able to explain the basis for

the opinion that he reached." Ibid.

      Contrary to the State's contention, our decision in McGuire is plainly

distinguishable from the matter at hand. In that case, the plastics engineer

merely suggested that the expert consider whether the "cliff" in the bag could

have been caused by an improperly placed blade. The expert then tested that

hypothesis completely on his own, using his standard methods. Here, on the

other hand, Sandford employed a completely new and untested machine to

personally examine the bullet fragment and the test bullets, included images

produced by BULLETTRAX in his report, and, as the trial court found, based

his ultimate conclusion, at least in part, on his use of this novel technology,

rather than the usual comparison microscope. Therefore, the State's argument

on this point fails.

      Because Sandford relied upon BULLETTRAX in arriving at his expert

opinion, we also agree with the trial court that a Frye hearing was necessary to

determine the reliability of this new technology. For evidence to be admissible



                                                                        A-0938-19T3
                                      35
under N.J.R.E. 702, "the expert must utilize a technique or analysis with 'a

sufficient scientific basis to produce uniform and reasonably reliable results so

as to contribute materially to the ascertainment of the truth.'" State v. J.R., 227

N.J. 393, 409 (2017) (quoting Kelly, 97 N.J. at 178).           "Thus, the test in

criminal cases [is] whether the scientific community generally accepts the

evidence." Harvey, 151 N.J. at 170. To establish general acceptance, "the

party proffering the evidence need not show infallibility of the techni que nor

unanimity of its acceptance in the scientific community." Cassidy, 235 N.J. at

492. "[T]he State's burden is to prove that the . . . test and the interpretation of

its results are non-experimental, demonstrable techniques that the relevant

scientific community widely, but perhaps not unanimously, accepts as

reliable." Harvey, 151 N.J. at 171.

      An application of the Frye test at an evidentiary hearing was necessary

in this case because BULLETTRAX is a new, untested device, operated by

Matchpoint, a novel software product.              As the trial court found,

"BULLETTRAX is a highly automated technology that does not merely

photograph the bullet's surface, as suggested by the State, but instead digitally

recreates the entire surface area." The parties did not provide the court with

any   judicial   opinions   or   authoritative   scientific   and   legal   writings

demonstrating the reliability of this machine.



                                                                            A-0938-19T3
                                        36
      In addition, neither Sandford nor Boyle were experts in the science

behind the BULLETTRAX system and, therefore, were unable to address

whether it provided reliable images. In that regard, both witnesses conceded

that BULLETTRAX created some degree of distortion when it "stitched

together" the images of the bullet fragment and the test bullets that Sandford

used to reach his conclusions. The trial court also correctly found that, for

many of these same reasons, "the reliability of Matchpoint" was "[e]qually

unproven at this time."

      Under these circumstances, we affirm the trial court's determination that

a Frye hearing was necessary to protect defendant's due process rights and

ensure that the images produced by BULLETTRAX were sufficiently reliable

to be admissible under N.J.R.E. 702.

                                       VI.

      Finally, we turn to the trial court's order requiring the State to provide

defendant with "the BULLETTRAX . . . and Matchpoint algorithms" in

advance of the Frye hearing, and the court's ruling that if BULLETTRAX is

found reliable following that hearing, Sandford "may testify that the evidence

bullet in this case is consistent with having been fired from the weapon seized

from . . . defendant[,] but may not opine as to any degree of scientific certainty

or to the exclusion of all other firearms." For the reasons that follow, we



                                                                         A-0938-19T3
                                       37
vacate each of these directives because we believe they were prematurely

issued.

      The trial court ordered the State to produce the BULLETTRAX and

Matchpoint algorithms based solely upon defense counsel's request. While it

is certainly possible that this information might be needed by defendant's

experts to evaluate the reliability of the new technology, the defense did not

present a certification from an expert in support of this claim for disclosure.

Thus, there is currently nothing concrete in the record to support the court's

conclusion that granting defendant "the opportunity to review the algorithms

and elicit testimony concerning" BULLETTRAX is necessary "in order to

completely explore and test the integrity of the images it produces."

      Under these circumstances, defendant is required to make a more

definitive showing of his need for this material to provide the court with a

rational basis to order the State to attempt to produce it. In that regard, the

trial court was aware that the algorithms are proprietary information within

UEFT's, rather than the State's, sole possession. While the court was open to

issuing a protective order to attempt to overcome UEFT's reluctance to

disclose this information to the State, the parties did not submit suggested

language to the court to assist it in attempting to craft and issue such an order.




                                                                          A-0938-19T3
                                        38
      Therefore, we vacate the court's order directing the turnover of the

algorithms, and remand the discovery issues to the court for further

consideration.    The court must promptly conduct a case management

conference with the parties to determine the most efficient way to proceed to

identify the types of information that must be shared by them in advance of the

Frye hearing. Resolution of discovery issues must be made after a N.J.R.E.

104 hearing to ensure the development of a proper, reviewable record that

supports the court's ultimate decision.

      We also hold that the court's order limiting the scope of Sandford's

possible testimony at trial was premature. At this point, the State has not

demonstrated that the BULLETTRAX and Matchpoint technology Sandford

relied upon is sufficiently reliable under Frye to be admissible at trial. If the

court ultimately concludes that the Frye standard has not been met, it is highly

unlikely that Sandford would testify at trial as an expert witness.

      On the other hand, if the court concludes that BULLETTRAX satisfies

the Frye test, Sandford's testimony at trial would be based on a completely new

technology. An expert's use of this technology was not addressed by any of

the judicial decisions from other jurisdictions cited by the court in limiting

Sandford's testimony. Those decisions only concerned witnesses who used the

standard comparison microscope.        Thus, if the court finds that the Frye



                                                                        A-0938-19T3
                                          39
standard has been met, Sandford's trial testimony may have a completely

different, and perhaps more solid, basis than that of the experts who had their

testimony limited by a court.

      Thus, we conclude that the court's placement of a limitation on

Sandford's testimony constituted an advisory opinion which the court did not

need to render at this stage of the proceedings. See G.H. v. Twp. of Galloway,

199 N.J. 135, 136 (2009) (noting that courts generally should not "answer

abstract questions or give advisory opinions").      We therefore vacate this

portion of the order. The court may revisit the issue of the scope of Sandford's

trial testimony following the Frye hearing.

                                      VII.

      In sum, we affirm the trial court's determination that a Frye hearing must

be held to determine the scientific reliability of the BULLETTRAX and

Matchpoint technology. We vacate the portions of the court's order concerning

discovery of the algorithms, and its ruling on the scope of Sandford's trial

testimony. We remand for further proceedings consistent with this opinion.

      Affirmed in part; vacated in part; and remanded.       We do not retain

jurisdiction.



+



                                                                        A-0938-19T3
                                      40
