                             UNPUBLISHED

                  UNITED STATES COURT OF APPEALS
                      FOR THE FOURTH CIRCUIT


                             No. 09-4520


UNITED STATES OF AMERICA,

                Plaintiff – Appellee,

           v.

THOMAS YU,

                Defendant – Appellant.



Appeal from the United States District Court for the Eastern
District of Virginia, at Alexandria. Gerald Bruce Lee, District
Judge. (1:08-cr-00196-GBL-1)


Argued:   October 29, 2010               Decided:   December 30, 2010


Before TRAXLER,   Chief   Judge,   and   DUNCAN   and   KEENAN,   Circuit
Judges.


Affirmed by unpublished opinion.        Judge Duncan wrote the
opinion, in which Chief Judge Traxler and Judge Keenan joined.


ARGUED: Lisa Hertzer Schertler, SCHERTLER & ONORATO, LLP,
Washington, D.C., for Appellant.    Jay V. Prabhu, OFFICE OF THE
UNITED STATES ATTORNEY, Alexandria, Virginia, for Appellee. ON
BRIEF: Neil H. MacBride, United States Attorney, Andrew
McCormack, Special Assistant United States Attorney, OFFICE OF
THE UNITED STATES ATTORNEY, Alexandria, Virginia, for Appellee.


Unpublished opinions are not binding precedent in this circuit.
DUNCAN, Circuit Judge:

       This appeal arises from a jury’s conviction of Thomas Yu on

three counts--alleging possession, receipt, and distribution of

child pornography--in violation of 18 U.S.C. §§ 2252A(a)(5)(B)

and    2252A(a)(2).            Yu   claims     the    district     court         abused     its

discretion         by   limiting     his   cross-examination           of    a   government

witness and by excluding a defense witness.                           He further argues

that       the     district     court      erred     with    respect        to     its    jury

instructions and violated Federal Rule of Criminal Procedure 43

by delivering an amended version of those instructions to the

jury in writing, despite his request that it be given in open

court.       For the reasons that follow, we affirm.



                                               I.

                                               A.

       In     August        2006,   federal     authorities       executed         a     search

warrant       at    the     Illinois    home    of    a    man   named      James      Faulds.

Investigators learned that Faulds had been operating a computer

file       server    that     allowed   individuals         to   upload      and       download

images       of     child    pornography.           They    further    learned          that   a

computer with an internet protocol address 1 registered to Yu’s


       1
       “Each computer connected to the Internet is assigned a
unique numerical address, otherwise known as an Internet
protocol or IP address, to identify itself and facilitate the
(Continued)
                                               2
Virginia home had, on July 20, 2006, uploaded forty-four files

containing images of child pornography to Faulds’s computer and

downloaded more than one hundred such files from it.

     Acting    on      this   information,     federal     and     state   law

enforcement officers executed a search warrant at Yu’s residence

in February 2007.        Agents seized a variety of items from his

home, including three desktop computers, two laptop computers,

and more than one hundred computer disks.            Forensic review of

these materials revealed, inter alia, more than 9,000 images of

child pornography and records of Internet searches for terms

related   to   child    pornography.       Investigators    also    uncovered

evidence that files containing images of child pornography had

been created in a folder associated with a peer-to-peer file

sharing program 2 on multiple occasions.         On October 15, 2008, a

grand jury indicted Yu on three counts of possessing, receiving,

and distributing child pornography.




orderly flow of electronic traffic.”         Peterson v. Nat’l
Telecomm. & Info. Admin., 478 F.3d 626, 628 (4th Cir. 2007).
     2
       “[P]eer-to-peer networks permit the users’ computers to
communicate directly with each other.” United States v. Morace,
594 F.3d 340, 343 (4th Cir. 2010) (quoting Metro-Goldwyn-Mayer
Studios Inc. v. Grokster, Ltd., 545 U.S. 913, 919-20 (2005))
(internal quotation marks omitted).



                                       3
                                      B.

     We briefly review the proceedings in the district court,

with particular attention to the disputes that gave rise to Yu’s

present    claims.      Shortly   after    his     indictment,   Yu   moved    for

disclosure    of     materials    related    to     the   case   against      him,

including    any     expert    testimony     the    government    intended      to

introduce at trial.           In response to Yu’s motion and with the

government’s agreement, the district court entered a discovery

order on October 23, 2008.            The order mandated a variety of

disclosures, including that both parties provide notice of any

anticipated expert testimony.

     On January 16, 2009, pursuant to the discovery order and

Federal Rule of Criminal Procedure 16(a)(1)(G), 3 the government

filed summaries of the testimony to be offered by its two expert

witnesses.        The government had earlier provided Yu with access

to   the    raw    computer    data   that    its     forensic    experts      had

evaluated.        Yu employed his own computer forensic examiner, a

woman named Tami Loehrs, to review this data.                However, Yu did




     3
       Rule 16(a)(1)(G) provides, in pertinent part, that “[a]t
the defendant’s request, the government must give to the
defendant a written summary of any testimony that the government
intends to use under Rules 702, 703, or 705 of the Federal Rules
of Evidence during its case-in-chief at trial.”           Expert
testimony is governed by Federal Rule of Evidence 702.



                                      4
not   disclose     any    prospective         expert    testimony--by            Loehrs    or

anyone else--prior to trial.

      Yu’s jury trial began on February 2, 2009.                        Consistent with

its   pre-trial    disclosures,          the      government      relied        heavily   on

expert   testimony       to   link    Yu     to   images    of    child        pornography.

Immigration      and     Customs      Enforcement       Agent         Joseph    Mizell,    a

forensic    computer      expert,       testified      about      a    variety     of    data

extracted from the computers seized from Yu’s home.

      For instance, after reviewing images of child pornography

found on one of those computers, Mizell noted that the same hard

drive contained documents that had “the name Thomas Christopher

Yu written on the bottom of them.”                  J.A. 253.          He observed that

some of these documents had apparently been accessed on the same

date as images of child pornography.                   Agent Mizell confirmed the

presence of similar documents containing Yu’s name on another

computer on which child pornography had been found.                             He further

testified that he had not found evidence that anyone else had

controlled that machine.

      Agent   Mizell      also     testified       about    the       seized     computers’

Internet browsing histories.               Agent Mizell explained that he had

extracted material related to child pornography from a larger

file containing a record of all websites visited on a particular

computer.     He       referred    to    a   government         exhibit    that     he    had

prepared    containing        those     portions       of   a    computer’s       browsing

                                             5
history related to child pornography.                 The government opted not

to   introduce    the    computer’s       complete    browsing      histories     into

evidence.

       Defense    counsel     cross-examined         Agent    Mizell      at   length,

eliciting a variety of concessions.                 Agent Mizell admitted that

he had not searched to see if digital records reflected that

friends of Yu, who might have had access to his computers, had

used the machines to download the illegal files.                       Agent Mizell

further conceded that he had focused his analysis on material

useful to the prosecution and had “omit[ted] certain images”

that were irrelevant to the search warrant.                  J.A. 311.

       Defense counsel also asked a series of questions about the

criteria Agent Mizell had followed when excerpting information

from    the      computers’     browsing        histories.           Agent      Mizell

acknowledged      that   he   had    “arbitrarily       picked      out    what   [he]

thought was relevant.”         J.A. 300.         He also stated, as he had on

direct examination, that the material presented to the jury did

not reflect the entirety of the computers’ browsing history.                          In

response to repeated queries by defense counsel, Agent Mizell

explicitly    acknowledged      on    at    least    seven    occasions        that    he

could   not   verify     whether     Yu    in   particular    had    conducted        the

searches reflected in the computers’ browsing histories or had

actually viewed any of the illegal images.                    See, e.g., J.A. at

297 (“As you sit here today, you can’t say that Mr. Yu ever

                                           6
viewed a single pornographic image; is that right?” “Correct.”);

id. at 317 (“I take it that you weren’t present and have no

personal knowledge as to who was using the computer [at] those

particular times; is that right?” “That’s right.”); id. at 326

(“[Y]ou can’t say anyone, Mr. Yu or [his friend] or anyone in

the     world    actually      viewed      that        particular       image       on    that

particular day?” “No.”).

       During     his    cross-examination             of     Agent    Mizell,        defense

counsel attempted to introduce three unauthenticated documents,

which were purportedly prepared by Yu’s forensic examiner, Tami

Loehrs.        Defense counsel asserted that the first such document

contained       some    of   the     raw   data        from    which    Agent        Mizell’s

browsing-history         excerpts     were       drawn.       Over     the    government’s

objection, the court gave defense counsel the opportunity to lay

foundation for the document.               Defense counsel asked Agent Mizell

a     series    of     questions     about       the    material.            Agent       Mizell

confirmed that Loehrs had accessed the data at issue, but he did

not know if that information was reflected in the document.                                The

document was not admitted into evidence.

       Shortly       after   the   first     document         was     rejected,      defense

counsel asked the court if he could pursue a line of questioning

designed “to show [Agent Mizell] that there is actually evidence

on the computer that . . . he chose to ignore that would really

show    that”    someone     other    than       Yu    had    downloaded      the     illegal

                                             7
images.      J.A. 316.        After hearing from both sides, the district

court     sustained     the    government’s        objection            to   that   line   of

questioning.

      Defense       counsel    later    referenced       a    second         document   that

allegedly      contained       part    of   the    seized         computer’s        Internet

browsing history from a particular date.                           When the government

objected, defense counsel was given another opportunity to lay

foundation.         Once again, Agent Mizell was able to confirm that

defense expert Loehrs had accessed the raw data, but he was

unable to speak to how she had prepared the document at issue.

The   government      renewed    its    objection        to       the    use   of   material

“which was not created by [Agent Mizell]” on cross-examination.

J.A. 323.      The district court sustained the objection, rejecting

in the process defense counsel’s argument that the material was

intended only to refresh Agent Mizell’s recollection.

      Part     way   through     defense        counsel’s         cross-examination        of

Agent Mizell, court adjourned for the day.                              That evening, Yu

filed notice, for the first time, of his intent to call Tami

Loehrs    as   an    expert    witness.         Styled       as    a    Rule   16(a)(1)(G)

notice, 4 Yu’s motion described Loehrs’s extensive background as a


      4
        Yu’s characterization of his motion notwithstanding,
defendants’ obligation to disclose information about expert
witnesses under certain circumstances arises under Federal Rule
of Criminal Procedure 16(b)(1)(C).   Here, the district court’s
discovery order created an independent obligation to divulge any
(Continued)
                                            8
computer         forensic     examiner.        It    explained      that    Loehrs    would

testify about images and other digital material recovered from

Yu’s       computers        and    describe    evidence      she    found   that     showed

additional users had access to those machines.                        The motion cited

Loehrs’s         “experience        and   training    in     the    field   of    computer

forensic analysis” as the basis for her testimony.                               J.A. 25C.

It included a twenty-page attachment, consisting of Loehrs’s CV

and a list of the more than one hundred cases in which she had

served as an expert witness.

       The next day, the district court ruled that Loehrs could

not testify as an expert witness.                     The court explained that Yu

had had months since the entry of the discovery order “to engage

an expert . . . and disclose any expert opinions” but had failed

to   do     so    in    a    timely    manner.       J.A.    328.      Defense     counsel

promptly responded that the expert notice had been filed purely

as a “prophylactic measure,” as Loehrs was in fact slated to

testify as a lay witness.                     J.A. 329.       He argued that Loehrs

would speak only to the “chain of custody” of the data that she

gathered         from   the       computers 5 and    would    “not    . .    .   offer an




planned expert testimony.     Yu does not dispute that he                               was
required to disclose expert testimony in advance of trial.
       5
        The data at issue included the two excerpts from
computers’ Internet browsing histories noted above, as well as a
(Continued)
                                               9
opinion . . . as to what happened and what didn’t happen.”                          J.A.

332.     He explained that, to the extent expert testimony was

necessary,      Yu    intended     to   rely    exclusively       on    the   testimony

provided by Agent Mizell.

       The   district      court    rejected       Yu’s    recharacterization        of

Loehrs’s testimony.            The court noted that Yu had engaged Loehrs

to review forensic data from the seized computers, that she had

done so, and that she had subsequently prepared charts for use

by the defense during trial.               The court expressed incredulity at

defense counsel’s claim that he intended “to prove that [Yu] was

not    guilty     .   .   .,     relying    sole[ly]      upon    the    government[]

witness’s       testimony.”        J.A.     331.        Citing    Yu’s    failure    to

disclose Loehrs’s existence until after the trial had started,

the    district       court    dismissed       Yu’s     efforts    to    reframe    the

substance of her testimony as “sandbagging” and precluded her

from testifying at trial.           J.A. 329.

       The defense ultimately called two lay witnesses to testify

on    Yu’s   behalf:      Yu’s    sister    and    Yu   himself.         Yu’s   defense

centered on his argument that a friend of his was responsible

for downloading the files recovered from the computers and that

he had been unaware of the files’ presence.                   When pressed by the



third document that purportedly showed                    when    certain       computer
files had been most recently accessed.



                                           10
government          on    cross-examination,      Yu    conceded    that,    on     his

theory, his friend had managed to secretly download many of the

illegal images over a period of years, from a computer located

in Yu’s bedroom, just “ten to twelve” feet from his bed.                          J.A.

482-83.        At        the   conclusion   of   Yu’s    testimony,   the    defense

rested.

       On February 4, 2009, the district court charged the jury in

open       court.        Its   jury   instructions      included,   inter   alia,    a

thorough      description        of   the   government’s     burden   of    proof   on

Count II, receipt of child pornography, § 2252A(a)(2). 6                      Before


       6
       The district court’s oral instruction on Count II was as
follows:

          Section 2252(a) Subsection(a)(2) of Title 18 of
     the United States Code provides in part that “it is a
     crime for any person who knowingly receives or
     distributes any child pornography that has been mailed
     or shipped or transported in interstate or foreign
     commerce by any means including by computer or any
     material that contains child pornography that has been
     mailed or shipped or transported in interstate or
     foreign commerce by any means, including by computer.”
          To sustain its burden of proof for the crime of
     receiving child pornography, the government must prove
     the following essential elements beyond a reasonable
     doubt.
          One, that the defendant did knowingly receive
     computer files or any other material that contained
     child pornography.
          And two, that such material of child pornography
     had   been   mailed  or  shipped   or  transported   in
     interstate or foreign commerce by any means, including
     by computer.
          And three, that at the time of such receipt of
     child pornography, the defendant believed that such
(Continued)
                                            11
beginning deliberations, the jury was provided a written copy of

the court’s instructions.

     The   following   day,    the     jury   sent   a   note    to   the   court,

asking “[i]f the defendant is aware of ‘another’ person doing

the act of ‘knowingly receiving,’ does it read on the defendant

Thomas Yu unlawfully and knowingly receiving.”                   J.A. 758.      At

about   4:00   pm,   the    district    court   convened        the   parties   to

discuss a response.        After hearing from both sides, the district

court proposed the following answer:

     Concerning receipt of child pornography Count Two, the
     essential elements of this offense are in Instruction
     16.     You may want to re-read Instruction 16.
     Additionally, mere knowledge that a crime is or has
     been   committed   does   not  constitute   “knowingly
     receiving.” In further response to your question, the
     Government must prove that the defendant was aware



     material constituted or contained child pornography as
     defined further in these instructions.
          With respect to Count II of the indictment, the
     government is only required to prove that the
     defendant knowingly received a single image. However,
     you have to be unanimous with respect to the image or
     images   of  child   pornography  you   determine  were
     received by--by the defendant for that count.
          Therefore, with respect to Count II as long as
     you find beyond a reasonable doubt that the defendant
     knowingly received a single image and that the other
     elements of the offense have been proved beyond a
     reasonable doubt, you must find the defendant guilty.

J.A. 641-42.    Yu has not challenged the propriety of this
instruction, nor has he argued that the court’s original written
instruction as to Count II--which was not included in the record
on appeal--was erroneous.



                                       12
     that child pornography was on his computer and he--the
     defendant knowingly received it with the intent to
     control it.     (E.g. view it or store it for later
     viewing by the defendant or someone else). If someone
     other   than   the   defendant   downloaded   the  child
     pornography   and   the   defendant   was   aware  child
     pornography was placed on his computer and the
     defendant intended to or did exercise control over it
     then the defendant has received child pornography.

J.A. 741-42, 759. 7

     Defense    counsel    objected      to    the   last   sentence   of   the

court’s response, arguing that it “propose[d] hypothetical facts

that the jury[]” would “take and apply to this case that weren’t

presented in evidence.”          J.A. 735.     The district court rejected

defense counsel’s argument and submitted the instruction to the

jury as drafted.         It simultaneously sent word to the jury to

return to the courtroom to be dismissed through the weekend. 8

     In light of the pending gap in the jury’s deliberations,

defense counsel requested the opportunity to file a motion on

the disputed instruction.         The district court consented, and, on

February 6, Yu filed his “motion to modify answer to jury’s

question,”     arguing    that    the   last    sentence    of   the   district

     7
       The record only contains a revised jury instruction, which
did not include the initial instruction’s disputed final
sentence. We have included the language of that sentence as it
appeared in Yu’s motion to amend the original instruction. The
government has not challenged the accuracy of that language.
     8
        Although February 5, 2009 was a Thursday, the court had
earlier advised the jury that court would not be in session on
Friday.



                                        13
court’s      supplemental        instruction         conflated     receipt       of    child

pornography with mere possession of child pornography.                                  J.A.

741.

       The court reconvened on February 9.                    After hearing argument

from both parties on the merits of Yu’s motion, the district

court,      without    conceding        error,      offered   to   “delete       the       last

sentence entirely.”             J.A. 749.        Defense counsel agreed that the

alteration would address Yu’s concerns and asked the court to

deliver the revised instruction orally.                       Noting that the jury

had been given the original supplemental instruction “for less

than    five       minutes,”     before       the    court    “took    it    back,”        the

district court instead opted to give the jury the updated answer

in   writing,       with    a   note     on   it    indicating     that     it   had       been

revised.       J.A. 749-50.         The revised instruction was dispatched

just before 10:00 am.             About one hour later the jury returned a

guilty verdict on all three counts.

       On    May     28,    2009,      the    district     court     sentenced        Yu    to

concurrent      terms      of   eighty-four         months’   imprisonment        on       each

count of conviction, to be followed by seven years of supervised

release.      This appeal followed.



                                              II.

       On    appeal,       Yu   argues    that      the   district    court      committed

reversible error by: (1) limiting his cross-examination of the

                                              14
government’s forensic expert, (2) precluding a defense witness

from testifying, and (3) providing the jury with a response that

broadened the theory on which he could be found guilty and then

delivering a corrective instruction in writing rather than in

open court.     We review the alleged violations in turn.

                                        A.

     Yu objects to the district court’s handling of his cross-

examination     of   Agent   Mizell,     who   testified        as   a   government

forensic computer expert.        Yu makes two arguments: (1) that the

district court “precluded an entire line of cross-examination

directed at errors and/or bias inherent in Mizell’s forensic

analysis,” Appellant’s Br. at 25, and (2) that “the district

court    erroneously   prevented       [him]   from   attempting         to    refresh

Mizell’s recollection,” id.

     Although the Sixth Amendment affords defendants the right

to confront witnesses against them, trial courts enjoy “wide

latitude insofar as the Confrontation Clause is concerned to

impose reasonable limits on . . . cross-examination.”                           United

States v. Ambers, 85 F.3d 173, 176 (4th Cir. 1996) (quoting

Delaware v. Van Arsdall, 475 U.S. 673, 679 (1986)); see also

United States v. Ayala, 601 F.3d 256, 273 (4th Cir. 2010).                          We

review    the   district     court’s    restrictions       on    Agent        Mizell’s

cross-examination      for   abuse     of    discretion,    United       States    v.

Scheetz, 293 F.3d 175, 184 (4th Cir. 2002), and find none.

                                        15
       Yu’s first argument is utterly unsupported by the record.

As    described      above,     the    transcript     of     Agent         Mizell’s    cross-

examination is replete with instances in which Mizell confirmed

that    he   could    not     verify     whether      Yu    had       in   fact    uploaded,

downloaded, or viewed images of child pornography.                            Agent Mizell

also acknowledged that he had presented a selective sample of

the    available     data,      conceded     that    he    had    culled       the    browser

histories with an eye toward developing the case against Yu, and

noted his failure to investigate other potential users of the

seized computers.          Agent Mizell could scarcely have been clearer

on these points.             In short, defense counsel was given broad

latitude to question Agent Mizell about potential errors and

biases and duly availed himself of the opportunity to do so.

Yu’s    claim      that   the    district     court       precluded         inquiries     into

these subjects lacks merit.

       To    the    extent      that   Yu    challenges       the      district       court’s

restriction of questions that relied on the raw data prepared by

the defense, his argument fails.                    It is a fundamental rule of

evidence      that    authentication          or    identification            of     physical

evidence      is     “a   condition         precedent      to     admissibility”          and

requires     “evidence       sufficient       to    support       a    finding     that   the

matter in question is what its proponent claims.”                            Fed. R. Evid.

901(a); see also United States v. Jones, 356 F.3d 529, 535 (4th

Cir. 2004).         Here, the district court found that because Agent

                                             16
Mizell       had    no    way       of   knowing        if     Yu’s        raw    data    accurately

reflected the material from which Mizell had worked, there was

not     a    proper       foundation            for     use     of       the     data     in    cross-

examination.          This determination was not an abuse of the court’s

discretion.           See      Ayala,      601    F.3d        at    272-73       (holding       that    a

district court did not abuse its discretion by requiring defense

counsel “to abide by . . . elementary [evidentiary] precepts”

during       cross-examination             “to        ensure        that    the    jury        was    not

misled”).

      By      the   same        token,     the        district       court       did     not    err    by

refusing to allow defense counsel to “refresh” Agent Mizell’s

recollections            of     his      earlier        analysis           by    referencing          the

defense’s       raw      data.           “The    matter        of     refreshing         a     witness’

recollection          and       the      manner        used        are     largely       within       the

discretion of the Trial Judge.”                         United States v. Cranson, 453

F.2d 123, 124 (4th Cir. 1971); see also Charles Wright & Victor

Gold, 28 Federal Practice & Procedure: Evidence § 6184, at 458-

59 (1993).          As Agent Mizell did not know if the document at

issue       contained         the   same    data       he     had    reviewed,         the     district

court could easily have determined that he could not have had

his recollection accurately refreshed by reviewing it.

                                                  B.

        Yu next challenges the district court’s refusal to allow

Tami Loehrs to testify as a lay witness.                                 We review the district

                                                  17
court’s choice of Rule 16 sanctions for abuse of discretion.

United States v. Fletcher, 74 F.3d 49, 54 (4th Cir. 1996).                            Yu

acknowledges that his disclosure of Loehrs’s expert testimony

was untimely and concedes that the district court was within its

discretion to exclude Loehrs as an expert.                     Appellant’s Br. at

36-37.     However, he renews his claim that Loehrs was slated to

testify as a lay witness and asserts that the exclusion of her

lay testimony was an abuse of discretion.                 Yu’s argument fails.

     The    Federal    Rules    of    Evidence     draw    a   clear     distinction

between    “lay”    testimony,       governed    by   Rule     701,    and     “expert”

testimony, governed by Rule 702, to avoid “the risk that the

reliability requirements set forth in Rule 702 will be evaded

through    the    simple    expedient    of     proffering     an     expert    in   lay

witness clothing.”          Fed. R. Evid. 701(c), advisory committee’s

note to 2000 Amendments; see also Fed. R. Evid. 702 (describing

expert testimony as that requiring “scientific, technical, or

other specialized knowledge”); Fed. R. Evid. 701(c) (proscribing

lay testimony “based on . . . knowledge within the scope of Rule

702”).     Yu’s effort to recast Loehrs as a lay witness suggests

just such an evasion.

     Even    if    defense    counsel     accurately       represented         Loehrs’s

testimony as going only to the “chain of custody” of data she

extracted    from     the    seized     computers,     such      testimony        would

inevitably have implicated expert knowledge within the scope of

                                         18
Rule    702.      Agent   Mizell’s        testimony      about    data     recovery

illustrates     the   point.        During       cross-examination        of    Agent

Mizell, defense counsel elicited an explanation of the technique

forensic examiners typically use to extract data.                   Agent Mizell

confirmed that forensic examiners typically use software called

“EnCase”   to   remove    data,     after      which   they   translate    the   raw

information into a viewable format.

       As Agent Mizell’s testimony shows, the process of forensic

data extraction requires “some specialized knowledge or skill or

education that is not in possession of the jurors.”                            United

States v. Johnson, 617 F.3d 286, 293 (4th Cir. 2010) (quoting

Certain Underwriters at Lloyd’s, London v. Sinkovich, 232 F.3d

200, 203 (4th Cir. 2000) (internal quotations omitted)); see

also United States v. Ganier, 468 F.3d 920, 926 (6th Cir. 2006)

(holding that testimony that would “require [the witness] to

apply    knowledge     and     familiarity        with       computers    and    the

particular forensic software well beyond that of the average

layperson” fell within the scope of Rule 702).                   In other words,

even if Loehrs had confined her testimony to her extraction and

translation of the data at issue, she would not have offered lay

opinion.       Yu’s assertions to the contrary strain credulity--

particularly     in   light    of   the     summary     of    Loehrs’s    testimony

contained in Yu’s Rule 16 notice and defense counsel’s explicit



                                          19
reference to Loehrs as “the expert . . . in the courtroom today”

during his cross-examination of Agent Mizell.                 J.A. 303.

     We have explicitly rejected attempts to make an end-run

around the Federal Rules of Evidence by blurring the distinction

between expert and lay testimony.             See Johnson, 617 F.3d at 293.

The district court did not abuse its discretion by preventing

such an effort here.

                                        C.

     Finally, Yu argues that the district court committed error

with respect to its jury instructions.               He urges in particular

that the district court impermissibly broadened the theory on

which he could be convicted of receipt of child pornography when

responding to a question from the jury.                  Although he concedes

that the deletion of the disputed sentence adequately addressed

the alleged error, he claims that the district court’s failure

to provide the revision orally violated his right under Federal

Rule of Criminal Procedure 43 to be present at “every trial

stage.”      Fed.    R.    Crim.   P.   43(a)(2).        We    review     preserved

challenges   to     jury   instructions      as   well   as    alleged     Rule   43

violations for harmless error.               United States v. Jeffers, 570

F.3d 557, 564 n.4 (4th Cir. 2009); United States v. Pratt, 351

F.3d 131, 138 (4th Cir. 2003).

     Yu claims that the final sentence in the district court’s

initial   response    to    the    jury’s    question    allowed   the     jury   to

                                        20
convict him for receipt of child pornography on a theory of mere

possession.        Even if that were so, any error was harmless.                The

jury   had   the    disputed   instruction      for    a   brief    period    before

being dismissed for a long weekend.                  When court reconvened on

Monday morning, the jury was promptly provided with a revised

instruction    the     substance   of        which    Yu   expressly    approved.

Deliberations proceeded for an hour before the jury reached its

verdict.      On these facts, we do not see how the challenged

instruction could have affected the outcome.

       Any Rule 43 error was similarly harmless.                   Neither Yu nor

his attorney were excluded from any part of the district court’s

consideration of the jury’s question or the preparation of the

court’s reply.        Cf. United States v. Rhodes, 32 F.3d 867, 874

(4th Cir. 1994).        To the contrary, both Yu and his counsel were

informed of the jury’s question, provided extensive input into

the    district      court’s    revised       response,      were     aware    what

instruction the jury was being given, and explicitly endorsed

the contents of the corrected instruction. 9               Once again, there is


       9
       At oral argument, Yu noted that the record does not
confirm whether the corrective note was ever received by the
jury.   Although it would certainly have been better if the
district court had created a clear record by delivering the
instruction orally, absent any indication that the note was not
properly delivered by the officer of the court to whom it was
entrusted, we assume that it was.   See United States v. Pratt,
351 F.3d 131, 138 (4th Cir. 2003).



                                        21
simply “no reasonable possibility that the practice complained

of might have contributed to the conviction.”    Pratt, 351 F.3d

at 138 (internal quotations omitted); see also United States v.

Solomon, 565 F.2d 364, 366 (5th Cir. 1978) (finding no prejudice

from submission of supplemental instruction to jury in writing

rather than orally).



                              III.

     For the foregoing reasons we affirm Yu’s conviction.

                                                            AFFIRMED




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