                              In the

    United States Court of Appeals
                For the Seventh Circuit
                    ____________________
No. 14-2019
UNITED STATES OF AMERICA,
                                                  Plaintiff-Appellee,

                                v.

WAYNE HILL,
                                              Defendant-Appellant.
                    ____________________

        Appeal from the United States District Court for the
           Northern District of Illinois, Eastern Division.
        No. 11 CR 850-1 — Sharon Johnson Coleman, Judge.
                    ____________________

  ARGUED SEPTEMBER 25, 2015 — DECIDED MARCH 21, 2016
                    ____________________

   Before WOOD, Chief Judge, and BAUER and EASTERBROOK,
Circuit Judges.
    WOOD, Chief Judge. They say the house always wins.
Wayne Hill found out the hard way that if you have robbed
a bank, that adage applies even if your trip to the casino was
just to get change. Hill was caught attempting to launder a
large amount of dye-stained currency, still in bank bands, by
stuffing the bills into a slot machine at the Horseshoe Casino
in Hammond, Indiana. He was ultimately convicted of bank
2                                                   No. 14-2019

robbery, money laundering, and transportation of stolen
funds.
    Hill filed pretrial motions to suppress his arrest, the con-
tents of his bags, and his statements at the time he was
caught. He also filed a motion in limine seeking to exclude
expert testimony under Federal Rule of Evidence 702 about
historical analysis of cellular telephone sites. Hill appeals the
district court’s denials of all four motions. Because the dis-
trict court properly resolved each one, we affirm its judg-
ment.
                                I
    On November 19, 2011, Hill walked into the Illiana Fi-
nancial Credit Union in Naperville, Illinois, pointed a pistol
at the teller, and ordered her to give him money. While Hill
threatened repeatedly to shoot her, another teller handed
over roughly $134,000 in cash. Hill fled the scene with a bag
full of stacks of wrapped bills.
    At that moment, Hill might have thought he was home
free. But there was something he did not know: one of the
tellers had managed to toss a dye pack into the bag along
with the cash. As Hill fled from the bank, it exploded, stain-
ing most of his haul a telltale red. Three days later, Hill
sought to remedy that problem. He drove to the Potawatomi
Hotel and Casino in Milwaukee, Wisconsin, where he sat
down in front of a slot machine and fed dye-stained bills into
it without playing the game. Instead, he cashed out, receiv-
ing vouchers in the amount of money he had put into the
machine. After repeating this maneuver on a number of ma-
chines, he redeemed the vouchers for unstained currency. He
managed to rid himself of $6,650 in stained bills that night.
No. 14-2019                                                 3

    On November 26, 2011, Hill tried to repeat his money-
laundering gambit. He strolled into the Horseshoe Casino in
Hammond, Indiana, with a backpack and a Santa hat filled
with thousands of dollars of dye-stained bills. He sat down
in front of a slot machine and began feeding it cash. But this
time, a slot attendant noticed what he was doing and
thought it strange. The slot attendant told Daniel Faulkner, a
casino security employee, that there was a guest at a slot ma-
chine with a bag containing a large amount of money. He
also told Faulkner that the money had red dye on it and that
the guest was sticking the money into the machine and cash-
ing it out without playing the slots.
    Faulkner called over the radio, and Monaye Perry, anoth-
er casino security employee, responded. By the time Perry
arrived, Hill had told a casino employee that one of his bills
had gotten stuck in the machine, and a slot attendant had
opened the machine to recover it. Faulkner told Perry what
Hill had been doing. Faulkner’s report made Perry suspi-
cious, because it was very unusual for a guest to be cashing
out of the machine without playing, not to mention for the
money to be stained red. Perry questioned Hill briefly. She
noted that he seemed nervous and hesitant and that he was
short with his responses. Perry then contacted Eugene
Kasper, her shift manager. As she did so, Hill abandoned the
slot machines and moved to the casino’s cash-out area.
    Kasper arrived with company: Hammond Police Lieu-
tenant Patrick McKechnie. McKechnie was moonlighting as
a security officer at the casino. Perry relayed Faulkner’s ac-
count to Kasper and McKechnie and noted that she had re-
ceived the information from Faulkner himself. McKechnie
and Kasper followed Hill to the cash-out area and confront-
4                                                  No. 14-2019

ed him. As Hill stood in line, McKechnie asked Hill why his
greenbacks were red and where he had gotten the money.
Hill did not respond to the first question, but in reply to the
second he said that he had found the money while changing
a tire near a lake.
     McKechnie found Hill’s story bizarre and suspicious. He
knew from his law-enforcement experience that bank em-
ployees often attempt to hide red dye-packs among stolen
money during robberies. He could see red dye-stained bills,
still wrapped in bank bands, in Hill’s hand. Surveillance
footage shows Kasper examining stacks of cash wrapped in
bank bands as several casino security personnel stand by. It
then shows Hill being led away, along with his bag and San-
ta hat, to an interview room. In the interview room, Hill was
questioned further and his bag was searched, revealing the
remainder of the money.
    Hill was indicted for money laundering, bank robbery,
and transporting stolen money in interstate commerce in vi-
olation of 18 U.S.C. §§ 1956(a)(1)(B)(i), 2113(a), (c), and (d),
and 2314. Before trial, Hill filed motions to suppress his ar-
rest, the search of his backpack and Santa hat, and his state-
ments to McKechnie. He also filed a motion in limine seek-
ing to exclude expert testimony regarding historical cell site
analysis under Rule 702 of the Federal Rules of Evidence.
The district court denied all four motions. A jury convicted
Hill on April 7, 2014, and he was sentenced to 360 months’
imprisonment. This appeal followed.
                              II
   Hill argues that his statements in the cash-out area and
the evidence seized incident to his arrest should have been
No. 14-2019                                                     5

suppressed because (1) Lieutenant McKechnie’s initial con-
versation with Hill was an arrest for which McKechnie did
not have probable cause; (2) if that encounter was not an ar-
rest, McKechnie did not have adequate reasonable suspicion
to perform an investigatory stop; and (3) McKechnie did not
have probable cause to remove Hill to the interview room
where the entirety of Hill’s store of stolen cash was discov-
ered. He also argues that the district court abused its discre-
tion in admitting Agent Joseph Raschke’s expert testimony
regarding historical cell site analysis.
                                A
    We look first at Hill’s three motions to suppress. We re-
view the district court’s rulings under a dual standard: we
apply the clear error standard to its factual determinations,
with special deference to the district court’s credibility de-
terminations, United States v. Villalpando, 588 F.3d 1124, 1127
(7th Cir. 2009); we take a de novo approach to its conclusions
of law. Id.
                                1
    Hill contends that his initial encounter with McKechnie
was an arrest, but we conclude that it was not. A seizure
qualifies an arrest only if “a reasonable person in the sus-
pect’s position would have understood the situation to con-
stitute a restraint on freedom of movement of the degree
which the law associates with formal arrest.” Abbott v. San-
gamon Cnty., Ill., 705 F.3d 706, 719 (7th Cir. 2013). This defini-
tion is somewhat circular. But it is clear that an arrest re-
quires at minimum that the subject’s “freedom of movement
is terminated or restrained by intentionally applied physical
force or submission to an assertion of authority.” Id. (citing
6                                                    No. 14-2019

California v. Hodari D., 499 U.S. 621, 626 (1991)). Importantly,
contrary to Hill’s arguments, the inquiry is objective and
“presupposes an innocent person.” Id. (citing United States v.
Drayton, 536 U.S. 194, 202 (2002)).
    It is hard to offer a crisp definition of what exactly consti-
tutes an arrest. But courts have made clear that “a brief, on-
the-spot stop on the street and a frisk for weapons” does not
qualify. Dunaway v. New York, 442 U.S. 200, 209 (1979) (citing
Terry v. Ohio, 392 U.S. 1, 19–20 (1968)). McKechnie’s interview
with Hill was not even as intrusive as a stop-and-frisk. He
made no “assertion of authority” and used no “physical
force.” Nor did his two questions contain any of the indicia
of a traditional arrest, no matter the number of casino securi-
ty personnel who were by then hanging around. At most, the
interaction represented an investigatory stop. Indeed, the
government maintains that it was consensual, and therefore
did not even constitute a seizure under the Fourth Amend-
ment. But we need not decide whether the interaction was
consensual: even if it were not, McKechnie’s questioning of
Hill qualified as a valid investigatory stop.
     An investigatory stop is valid when supported by “a rea-
sonable, articulable suspicion that criminal activity is afoot.”
Illinois v. Wardlow, 528 U.S. 119, 123 (2000). A “reasonable,
articulable suspicion” is less than probable cause; it requires
only “a minimal level of objective justification.” Id. In decid-
ing whether the officer’s suspicion was justified, the court
must consider the “totality of the circumstances” surround-
ing the stop. United States v. Arvizu, 534 U.S. 266, 273 (2002).
The officer may “draw on [his or her] own experience and
specialized training to make inferences from and deductions
about the cumulative information available ... that might
No. 14-2019                                                   7

well elude an untrained person.”       Id. (internal quotation
marks omitted).
    The district court found as a fact that McKechnie had
learned a great deal before he confronted Hill. Perry had told
him directly that (1) a slot attendant had seen Hill trying to
cash out a large amount of red-dyed money through a slot
machine; (2) the slot attendant had told Faulkner what he
saw; (3) Faulkner had told Perry; and (4) Perry had ques-
tioned Hill and found his answers and demeanor suspicious.
Additionally, McKechnie knew from experience that dye
packs are used to mark stolen currency. He said that he
would find it suspicious if someone were using a slot ma-
chine “as a change machine.” None of these factual findings
were clearly erroneous. The information McKechnie pos-
sessed represented far more than “a minimal level of objec-
tive justification.” See Wardlow, 528 U.S. at 123. It was suffi-
cient to arouse reasonable suspicion that Hill had committed
a crime, and thus to make McKechnie’s interaction with Hill
in the cash-out area a valid investigatory stop.
                               2
   Hill argues that even if his initial interview with
McKechnie was a valid investigatory stop, he was arrested
without probable cause when he was escorted to the inter-
view room. This argument can succeed only if, at that time,
McKechnie lacked probable cause to believe Hill had com-
mitted a crime. But the record supports a finding of probable
cause by then. Hill was therefore validly arrested when he
was taken to the interview room.
    An arrest is lawful under the Fourth Amendment so long
as it is made based on probable cause. Rodriguez v. United
8                                                    No. 14-2019

States, 135 S. Ct. 1609, 1621 (2015). Probable cause “means
facts and circumstances within the officer’s knowledge that
are sufficient to warrant a prudent person, or one of reason-
able caution, in believing, in the circumstances shown, that
the suspect has committed, is committing, or is about to
commit an offense.” Michigan v. DeFillippo, 443 U.S. 31, 37
(1979). Whether probable cause exists is a “commonsense,
practical question” made considering the totality of the cir-
cumstances. Illinois v. Gates, 462 U.S. 213, 230–31 (1983).
When a court reviews probable cause determinations, the
evidence must be weighed “as understood by those versed
in the field of law enforcement.” Id. at 232 (quoting United
States v. Cortez, 449 U.S. 411, 418 (1981)).
    Once he approached Hill in the cash-out line, McKechnie
could see that Hill was holding a stack of currency stained
with red dye and wrapped in bank bands. Based on Perry’s
report, his own observations, and his prior experience,
McKechnie surmised that the money was from a bank rob-
bery and that Hill was trying to launder it. McKechnie asked
Hill why the money was dyed red and where he had ob-
tained it. Hill initially refused to answer either question, but
then offered the unlikely story that he found it while chang-
ing a tire by a lake. Hearing this, McKechnie was justifiably
suspicious. A reasonably prudent person in McKechnie’s po-
sition would think that Hill had committed or was commit-
ting a crime. See, e.g., United States v. Curry, 538 F.3d 718, 730
(7th Cir. 2008) (search warrant based largely on observation
of suspect handling red-dyed currency “clearly supported a
determination of probable cause”). McKechnie therefore had
probable cause to arrest Hill.
No. 14-2019                                                  9



                              3
    Finally, the search that revealed Hill’s remaining currency
was unobjectionable. A search incident to arrest is valid if it
does not extend beyond “the arrestee’s person and the area
within his immediate control.” Arizona v. Gant, 556 U.S. 332,
339 (2009) (internal quotation marks omitted). The zone of
“immediate control” includes “the area from within which
[the suspect] might gain possession of a weapon or de-
structible evidence.” Id. When he was detained, Hill was
holding the bag containing his hoard of dye-stained cash
and was plainly exercising immediate control over it.
McKechnie’s search was therefore a permissible search inci-
dent to arrest, and the district court was correct to deny
Hill’s motions to suppress.
                              B
   Hill’s other argument focuses on expert testimony from
Agent Raschke about historical cell-site analysis. This testi-
mony, he contends, violated Federal Rule of Evidence 702
because the district court improperly applied the rule and
the Supreme Court’s framework in the line of cases begin-
ning with Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579,
589 (1993). We review the analytical approach the district
court took de novo and its application of that framework to
the facts before it for abuse of discretion. Lees v. Carthage
Coll., 714 F.3d 516, 520 (7th Cir. 2013).
    Historical cell-site analysis uses cell phone records and
cell tower locations to determine, within some range of error,
a cell phone’s location at a particular time. A cell phone is
essentially a two-way radio that uses a cellular network to
10                                                    No. 14-2019

communicate. Aaron Blank, The Limitations and Admissibility
of Using Historical Cellular Site Data to Track the Location of A
Cellular Phone, 18 RICH. J.L. & TECH. 3, 5 (2011). Each cell
tower covers a certain geographic area. That geographic area
depends upon “the number of antennas operating on the cell
site, the height of the antennas, topography of the surround-
ing land, and obstructions (both natural and manmade).” Id.
In urban areas, cell towers may be located every one-half to
one mile, while cell sites in rural areas may be three to five
miles apart. Id. When a cell phone user makes a call, the
phone generally “connect[s] to the cell site with the strongest
signal,” although “adjoining cell [towers] provide some
overlap in coverage.” Id. While the proximity of the user is a
significant factor in determining the cell tower with which
the cell phone connects, it is not the only one. Id. Other fac-
tors include the towers’ technical aspects, including geogra-
phy and topography, the angle, number, and directions of
the antennas on the sites, the technical characteristics of the
relevant phone, and “environmental and geographical fac-
tors.” Id. at 7.
    The parties here do not dispute that testimony about his-
torical cell-site analysis is expert testimony. That proposition
is not, however, universally applied, and perhaps not even
universally accepted. Some circuits have treated some kinds
of historical cell-site analysis as lay testimony. See, e.g., Unit-
ed States v. Graham, 796 F.3d 332, 364 (4th Cir. 2015) (finding
no abuse of discretion in admitting Sprint/Nextel employee’s
lay testimony that cell phones connect to the tower emitting
the strongest signal and cell towers in urban areas have a
two-mile maximum range, and law enforcement officer’s lay
testimony and maps regarding the defendant’s location
based on cell phone records and cell sites); United States v.
No. 14-2019                                                  11

Henderson, 564 F. App’x 352, 364 (10th Cir. 2014) (nonprece-
dential) (law enforcement agent’s plotting of the defendant’s
locations through historical cell-site analysis was proper lay
testimony so long as the agent did not testify about how cell
towers operate), reh’g en banc granted, 624 F. App’x 75 (4th
Cir. 2015).
    Agent Raschke’s testimony in this case included state-
ments about how cell phone towers operate. In our view, this
fits easily into the category of expert testimony, such that
Rule 702 governs its admission. See Graham, 796 F.3d at 364
(holding historical cell-site analysis testimony about how cell
phones and towers connect “clearly ‘based on scientific,
technical, or specialized knowledge within the scope of Rule
702.’” (quoting FED. R. EVID. 701(c))); United States v. Yeley-
Davis, 632 F.3d 673, 684 (10th Cir. 2011) (“[T]estimony con-
cerning how cell phone towers operate constituted expert
testimony because it involved specialized knowledge not
readily accessible to any ordinary person.”).
    When evaluating whether an expert’s testimony should
be admitted, a court must consider whether the expert’s tes-
timony is “supported by appropriate validation” and “will
assist the trier of fact to understand or determine a fact in
issue.” Daubert, 509 U.S. at 590–92; Kumho Tire Co. v. Carmi-
chael, 526 U.S. 137, 147 (1999) (extending the Daubert’s “gate-
keeping function” to all expert evidence). Rule 702’s purpose
is to “establish[] a standard of evidentiary reliability.” Kumho
Tire, 526 U.S. at 149 (quoting Daubert, 509 U.S. at 590). The
Supreme Court emphasized the importance of carefully vet-
ting expert testimony, noting that it “can be both powerful
and quite misleading because of the difficulty in evaluating
it.” Daubert, 509 U.S. at 595 (quoting Jack B. Weinstein, Rule
12                                                   No. 14-2019

702 of the Federal Rules of Evidence Is Sound; It Should Not Be
Amended, 138 F.R.D. 631, 631–32 (1991)).
    Rule 702 sets out four criteria for the admission of expert
testimony:
        (a) the expert’s scientific, technical, or other special-
     ized knowledge will help the trier of fact to understand
     the evidence or to determine a fact in issue;
        (b) the testimony is based on sufficient facts or data;
        (c) the testimony is the product of reliable principles
     and methods; and
       (d) the expert has reliably applied the principles and
     methods to the facts of the case.
FED. R. EVID. 702. In applying those criteria, courts must also
bear in mind the fact that “the gatekeeping inquiry must be
tied to the facts of a particular case.” Kumho Tire, 526 U.S. at
150 (internal quotation marks omitted). The trial judge has
“broad latitude” to determine how to evaluate expert testi-
mony and whether to hold an evidentiary hearing in any
particular case. Id. at 153.
    District courts that have been called upon to decide
whether to admit historical cell-site analysis have almost
universally done so. See United States v. Jones, 918 F. Supp. 2d
1, 5 (D.D.C. 2013) (collecting cases). Ironically, one of the few
exceptions involved Agent Raschke himself. See United States
v. Evans, 892 F. Supp. 2d 949, 956 (N.D. Ill. 2012) (admitting
traditional historical cell-site analysis, but rejecting Raschke’s
novel and “wholly untested” theory of “granulization”). The
government argues that the numerous district court deci-
sions to admit historical cell-site analysis constitute “general
No. 14-2019                                                   13

acceptance” of the technique. But judicial acceptance is not
relevant; what matters is general acceptance in the relevant
expert (scientific or otherwise) community. See Daubert, 509
U.S. at 594; Gen. Elec. Co. v. Joiner, 522 U.S. 136, 148 (1997)
(Breyer, J., concurring) (“[J]udges are not scientists and do
not have the scientific training that can facilitate the making
of such decisions.”).
    No federal court of appeals has yet said authoritatively
that historical cell-site analysis is admissible to prove the lo-
cation of a cell phone user. The Sixth Circuit gave the tech-
nique an unfavorable appraisal recently in United States v.
Reynolds, 626 F. App’x 610, 616–17 (6th Cir. 2015) (nonprece-
dential). Because the government there used historical cell-
site analysis to prove that certain people were not in a certain
area at a particular time, the court did not need to rule on the
technique’s reliability for proving where a person was at a
given time. The court noted, however, that claims of success-
ful use by law enforcement personnel were “precisely the
sort of ‘ipse dixit of the expert’ testimony that should raise a
gatekeeper’s suspicion,” were it “not subject to independent
peer review,” and “fail[ed] to establish an error rate with
which to assess reliability because there was no information
on how many times the technique was employed unsuccess-
fully.” Id. at 616 (quoting Kumho Tire, 526 U.S. at 157). The
Fifth Circuit, in contrast, has affirmed the admission of his-
torical cell-site analysis under Rule 702 to prove an individ-
ual’s location. See United States v. Schaffer, 439 F. App’x 344,
347 (5th Cir. 2011) (nonprecedential). But the Sixth Circuit
singled out Schaffer for criticism in Reynolds. 626 F. App’x at
616–17. And even the Fifth Circuit only remarked that
“[t]estimony established that the field is neither untested nor
14                                                No. 14-2019

unestablished.” 439 F. App’x at 347. This is hardly a ringing
endorsement.
    The contested cell-site analysis in Hill’s case covers two
days. The first is November 14, 2011. Agent Raschke testified
that Hill’s cell phone records and the locations of relevant
cell towers indicated that on that day, Hill’s T-Mobile cell
phone used a tower that was roughly a mile and half from
the Credit Union that was later robbed. Agent Raschke also
used historical cell-site analysis to trace the whereabouts of
Hill’s phone on November 19, 2011, the day of the robbery.
Most significantly, Agent Raschke testified that at 11:54 am—
16 minutes after the robber fled the Credit Union—Hill’s
Nextel phone engaged a tower in Naperville, Illinois, that
was located approximately 11 miles east of the Credit Union
and 35 miles south of Hill’s residence. Agent Raschke then
traced connections between Hill’s cell phone and towers
moving north along the interstate. The clear implication of
the testimony was that Hill’s cell phone was in the general
area of the Credit Union shortly after the robbery, and then
moved rapidly northward along the highway immediately
afterward. It wound up near his residence at 12:28 pm before
moving north again at 1:08 pm and ending at his work ad-
dress at 1:33 pm.
    The government used Agent Raschke’s historical cell-site
analysis against Hill for two purposes at closing. The first
was to argue that Hill’s alibi statement to Agent Hoogland—
that he was at work at 12:30 pm on November 19, 2011, and
therefore could not have been at the Credit Union at 11:38
am—was a lie. As this involved proving where Hill was not,
rather than where he was, this use is uncontroversial. See,
e.g., Reynolds, 626 F. App’x at 617. But, more problematically,
No. 14-2019                                                     15

the government used Agent Raschke’s testimony to argue
that Hill was in the general vicinity of the Credit Union 16
minutes after it was robbed on that day, and that he then
drove rapidly north back to his house, before continuing on
to work 40 minutes later.
    In his trial testimony, Agent Raschke emphasized that
Hill’s cell phone’s use of a cell site did not mean that Hill was
right at that tower or at any particular spot near that tower.
This disclaimer saves his testimony. Historical cell-site anal-
ysis can show with sufficient reliability that a phone was in a
general area, especially in a well-populated one. It shows the
cell sites with which the person’s cell phone connected, and
the science is well understood. Evans, 892 F. Supp. 2d at 956
(noting that methods of “historical cell site analysis can be
and have been tested by scientists”). The technique requires
specialized training, which Agent Raschke has and has em-
ployed successfully on hundreds of occasions. A mathemati-
cal error rate has not been calculated, but the technique has
been subjected to publication and peer criticism, if not peer
review. See, e.g., Matthew Tart et al., Historical Cell Site Analy-
sis – Overview of Principles and Survey Methodologies, 8 DIGITAL
INVESTIGATION 185–86 (2012); Blank, 18 RICH. J.L. & TECH. at
3–5; Herbert B. Dixon Jr., Scientific Fact or Junk Science? Track-
ing A Cell Phone Without GPS, 53 JUDGES’ J. 37 (2014). The ad-
vantages, drawbacks, confounds, and limitations of histori-
cal cell-site analysis are well known by experts in the law en-
forcement and academic communities. Agent Raschke de-
scribed many of them at trial.
   Nonetheless, we have some concerns about Agent
Raschke’s testimony. On cross-examination, he admitted that
he did not know any of the particular characteristics of the
16                                                 No. 14-2019

cell tower with which Hill’s phone connected at 11:54 am,
including its power or the direction its antennae were facing.
He did not perform any tests of that cell tower’s area of sig-
nal coverage. Based on his experience, he disputed defense
counsel’s suggestion that a cell phone could connect from 20
or 10 miles away from a particular cell site, but he admitted
that it could travel “over 5 miles.” On re-direct he stated that
his experience was that the range of Chicago area towers
was “very limited,” and that he had never, in hundreds of
investigations in Chicago, seen a cell phone “jump” to con-
nect with a cell tower 20 miles away. Based on this testimony,
the jury could reasonably and reliably infer that at 11:54 am
on November 19, 2011, Hill was within a five-mile radius of
the cell tower located 11 miles east of the Credit Union. The
testimony is relevant and probative, and therefore somewhat
helpful to the trier of fact—even if not that helpful.
    Our concern is that the jury may overestimate the quality
of the information provided by this analysis. We therefore
caution the government not to present historical cell-site ev-
idence without clearly indicating the level of precision—or
imprecision—with which that particular evidence pinpoints
a person’s location at a given time. The admission of histori-
cal cell-site evidence that overpromises on the technique’s
precision—or fails to account adequately for its potential
flaws—may well be an abuse of discretion. In this case, how-
ever, Agent Raschke’s testimony on both direct and cross-
examination made the jury aware not only of the technique’s
potential pitfalls, but also of the relative imprecision of the
information he gleaned from employing it in this case. The
science and methods upon which the technique is based are
understood and well documented. Admitting Agent
Raschke’s testimony was therefore not an abuse of the dis-
No. 14-2019                                                17

trict court’s considerable discretion under either Rule 702 or
Rule 403.
                               III
   Because the district court did not err in denying any of
Hill’s four motions, we AFFIRM its judgment.
