                               In the

    United States Court of Appeals
                 For the Seventh Circuit
                     ____________________
No. 19-1295
UNITED STATES OF AMERICA,
                                                   Plaintiff-Appellee,
                                 v.

SHAWN M. DEWITT,
                                               Defendant-Appellant.
                     ____________________

         Appeal from the United States District Court for the
         Northern District of Indiana, South Bend Division.
             No. 3:17-cr-110 — Jon E. DeGuilio, Judge.
                     ____________________

 ARGUED SEPTEMBER 25, 2019 — DECIDED NOVEMBER 27, 2019
                ____________________

   Before FLAUM, SYKES, and SCUDDER, Circuit Judges.
    SCUDDER, Circuit Judge. Trials often require jurors, as lay-
people considering evidence, to draw inferences based on
their life experiences. The duty is most unenviable in cases re-
quiring jurors to view images of child sexual abuse. After do-
ing so in Shawn Dewitt’s trial, the jury found him guilty of
child pornography oﬀenses. Dewitt argues the government’s
evidence was insuﬃcient because the jury heard no expert
testimony (from a medical doctor, for example) about the age
2                                                 No. 19-1295

of girls depicted in images sent from his cellphone. While
some cases may present close calls that beneﬁt from expert
evidence, this one does not. The jury heard and saw more
than enough to make a reliable ﬁnding that Dewitt possessed,
produced, and distributed images of children. We aﬃrm.
                              I
                              A
    Shawn Dewitt was living in Lafayette, Indiana with his ﬁ-
ancée, three-year-old son, and four-year-old daughter when
he began chatting with Timothy Palchak on an anonymous
phone application. The two men met in an online group called
“Open Family Fun.” Unbeknownst to Dewitt, Palchak was an
undercover oﬃcer and member of the FBI’s Internet Crimes
Against Children Task Force who had targeted the group for
a sting operation because its name suggested sexual interest
in children.
    In their online conversation, Dewitt told Oﬃcer Palchak
about his children. Oﬃcer Palchak reciprocated by conveying
information about his (ﬁctitious) nine-year-old daughter.
Dewitt admitted to sexually abusing his four-year-old daugh-
ter but made plain he preferred slightly older girls—“devel-
opment age” girls at the beginning of puberty, as he put it. He
oﬀered to send images of himself abusing his daughter if Of-
ﬁcer Palchak would do the same.
    While repeatedly soliciting images of Oﬃcer Palchak’s
daughter, Dewitt also sent one video and one still image of
fully nude girls. Dewitt accompanied the images with de-
scriptions of the sexual acts he would like to see Oﬃcer Pal-
chak’s nine-year-old daughter perform.
No. 19-1295                                                     3

    In time the FBI arrested Dewitt and seized and searched
his phone. The search uncovered the images sent to Oﬃcer
Palchak and a photo of Dewitt engaged in a sexual act with
his four-year-old daughter. All of this led to a grand jury
charging Dewitt with three counts relating to the production,
distribution, and possession of child pornography in viola-
tion of 18 U.S.C. §§ 2251(a), 2252(a)(2), and 2252(a)(4)(B). He
proceeded to trial, and a jury returned a guilty verdict on all
counts. The district court sentenced Dewitt to 30 years’ im-
prisonment.
                                B
    At trial Dewitt objected to the district court’s admission of
the photograph and video he sent to Oﬃcer Palchak, which
formed the basis of the distribution charge. He contends that
the law required the government to present expert testimony
about the subjects’ ages before the images could be received
into evidence. The court overruled the objection but noted
that, upon the return of a guilty verdict, Dewitt could raise the
issue in a new motion for a judgment of acquittal under Fed-
eral Rule of Criminal Procedure 29.
    After the jury returned its verdict, the district court denied
Dewitt’s Rule 29 motion. It rejected the argument that the two
images were such a close call to require expert testimony to
establish the subjects’ status as minors. From his own review
of the images, the district judge concluded that the appear-
ance of the undeveloped girls—who had “narrow shoulders
and thin hips and thighs”—allowed non-experts to determine
they were younger than 18. As to the video, the judge added
that the jury “had the added beneﬁt of watching [the girl’s]
immature demeanor and hearing her child-like voice.” The
court therefore determined that suﬃcient evidence supported
4                                                 No. 19-1295

the verdict on the distribution charge because a rational jury
could ﬁnd beyond a reasonable doubt that the two images de-
picted girls under 18.
                              II
                              A
    In reviewing the denial of the Rule 29 motion for judgment
of acquittal, we apply the same standard as the district court.
The overarching question is whether there was suﬃcient evi-
dence to support the guilty verdict. See United States v.
Khilchenko, 324 F.3d 917, 921 (7th Cir. 2003). We “consider the
evidence in the light most favorable to the Government,” and
will reverse “only when the record contains no evidence, re-
gardless of how it is weighed, from which the jury could ﬁnd
guilt beyond a reasonable doubt.” United States v. Blassingame,
197 F.3d 271, 284 (7th Cir. 1999).
    We have avoided requiring expert testimony in child por-
nography cases to establish an unidentiﬁed individual’s sta-
tus as a minor. We agree with other circuits that answering
whether expert testimony is needed “must be determined on
a case by case basis.” United States v. Katz, 178 F.3d 368, 373
(5th Cir. 1999). In some cases, the question may be diﬃcult
and all but require the government to present expert evidence
as part of carrying its burden of proving age beyond a reason-
able doubt. See id.
    In many cases, however, the fact that the unidentiﬁed sub-
ject is a child will be obvious from appearance. Expert testi-
mony is unnecessary—and may even be properly excluded—
if people “of common understanding, are as capable of com-
prehending the primary facts and of drawing correct conclu-
sions from them as are witnesses possessed of special or
No. 19-1295                                                    5

peculiar training, experience, or observation in respect of the
subject under investigation.” Salem v. U.S. Lines Co., 370 U.S.
31, 35 (1962); see also Cyrus v. Town of Mukwonago, 624 F.3d
856, 864 (7th Cir. 2010). If the matter is within the jurors’ un-
derstanding, the expert testimony is not “specialized
knowledge” that “will help the trier of fact,” as required by
Federal Rule of Evidence 702.
    These principles apply with full force in child pornogra-
phy cases. Jurors are capable of drawing on their own percep-
tions to determine a subject’s age because these types of as-
sessments are “regularly made in everyday life.” United States
v. Batchu, 724 F.3d 1, 8 (1st Cir. 2013) (explaining that expert
testimony was unnecessary because a “multiplicity of indica-
tors”—such as the victim’s gait, conversation with the defend-
ant, voice, and general demeanor—would indicate her age to
a layperson); see also United States v. Haymond, 672 F.3d 948,
960 (10th Cir. 2012) (holding that expert testimony was unnec-
essary because the photographs were known child victims
but also explaining that jurors at times can determine age for
themselves “particularly when the subjects [are] suﬃciently
young”).
    We have reached the same conclusion in similar circum-
stances. In United States v. Lacey, we held that “expert evi-
dence is not required to prove the reality of children por-
trayed in pornographic images.” 569 F.3d 319, 324–25 (7th Cir.
2009). As the First Circuit put the same point, the fact that ex-
perts are not required for the “more technical subject of
whether a sexually explicit image depicts a real or computer-
generated child,” “suggests that we should similarly not re-
quire the government to provide an expert witness for an
6                                                   No. 19-1295

assessment [about a child’s age, which is] frequently and rou-
tinely made in day-to-day experience.” Batchu, 724 F.3d at 8.
    Beyond appearance, the factﬁnder may consider other
contextual factors in determining age. Those factors include a
defendant’s own stated sexual preferences. Consider, for ex-
ample, the Eighth Circuit’s reasoning in United States v.
O’Malley, 854 F.2d 1085 (8th Cir. 1988). The evidence there
showed that the defendant described the girls in the pictures
he unwittingly sent to a postal inspector as 12 years old and
younger than nine. See id. at 1086. The girl in one photo wore
braces and the other “appeared diminutive in all her bodily
proportions.” Id. at 1087 n.3. The defendant’s own descrip-
tion, combined with what the pictures themselves showed,
was suﬃcient to sustain a child pornography conviction. Id.;
accord United States v. Broyles, 37 F.3d 1314, 1317, 1319 (8th
Cir. 1994) (aﬃrming a jury’s verdict in part because the de-
fendant’s expressed preference for “young white females be-
tween the ages of 11 and 15, just developing and not totally
developed” supported the ﬁnding that a video of unidentiﬁed
individuals ﬁt that description and showed the subjects to be
minors).
                               B
    The trial record contained ample evidence to support the
jury’s decision to convict Dewitt on the distribution count. Ju-
rors bring to their service the totality of lived experiences not
only as adults (and, more speciﬁcally, as parents, guardians,
grandparents, aunts, and uncles), but also as once themselves
children too. All of these experiences instill the knowledge,
judgment, and common sense requisite to tell the diﬀerence
between a young child, a girl in the ﬁrst stages of puberty, and
someone who has reached the age of 18. That a particular
No. 19-1295                                                  7

individual has entered puberty informs the inquiry but does
not automatically make expert testimony required as part of
determining age. Whether a jury can answer the question
must be assessed on a case-by-case basis, and here the district
court got it right in concluding that the answer was suﬃ-
ciently clear to eliminate any need for expert testimony.
   Recall that the district judge himself examined each image.
He considered the appearance of the girls in the photograph
and video in deciding that the jury could make the age ﬁnding
on its own. Even more speciﬁcally, the judge determined
that—based on physical appearances alone—the “jury would
be able to determine based on routine experience that these
undeveloped slender girls (with narrow shoulders and thin
hips and thighs) were not as old as eighteen.” United States v.
Dewitt, No. 3:17-CR-110 JD, 2018 WL 5961723, at *3 (N.D. Ind.
Nov. 14, 2018). For the video, the jury also had the oppor-
tunity to observe the girl’s “immature demeanor” and hear
her “child-like voice.” Id.
    There was more too. The girls’ status as minors found re-
inforcing support in contextual evidence revealing Dewitt’s
sexual preferences. In his online chats with Oﬃcer Palchak,
Dewitt stated that he liked “development age,” barely post-
pubescent girls. In terms unnecessary to recount here, he then
described in graphic detail his physical preferences, which
corresponded suﬃciently with that age and the appearance of
the girls in the images. What is more, the sexual acts per-
formed by the girl in the video were the same ones Dewitt
urged Oﬃcer Palchak to have his ﬁctitious nine-year-old
daughter perform.
  All of this left the jury and the district court—and now
us—of the clear view that expert testimony was not necessary:
8                                                   No. 19-1295

the girls appeared far from 18 and Dewitt’s own statements
allowed a jury ﬁnding that each child ﬁt his preferences.
                               III
    We also need to address Dewitt’s contention that a gap in
the government’s showing of his cell phone’s chain of custody
meant that the district court should have never admitted the
images found on it into evidence at trial. What happened is
straightforward. Upon Dewitt’s arrest, FBI Agent Richard Da-
vies turned the phone oﬀ, took it to his oﬃce, and put it on
his desk. While not itself locked, Agent Davies’s oﬃce is part
of a larger FBI oﬃce accessible to only ﬁve or six employees
with the requisite personal ID card and access code. Agent
Davies was the last to leave the night of Dewitt’s arrest and
the ﬁrst to arrive the next morning. Upon returning he found
the phone exactly as he had left it. At that point Agent Davies
logged the phone into evidence and sent it to an FBI forensic
facility.
    To be admissible, “the physical exhibit being oﬀered [must
be] in substantially the same condition as when the crime was
committed.” United States v. Moore, 425 F.3d 1061, 1071 (7th
Cir. 2005). The chain of custody does not need to be perfect.
Rather, the government needs to show that it took “reasona-
ble precautions” to preserve the evidence—a standard that
does not require excluding all possibilities of tampering. Id.
Absent any evidence to the contrary, when property is in po-
lice custody a presumption arises that the evidence has not
been tampered with. See United States v. Tatum, 548 F.3d 584,
587 (7th Cir. 2008). Any gaps in the chain of custody or spec-
ulative claims of tampering go to the weight of the evidence
rather than its admissibility. See United States v. Lee, 502 F.3d
691, 697 (7th Cir. 2007).
No. 19-1295                                                    9

    We see no abuse of discretion in the district court’s admis-
sion of Dewitt’s cell phone at trial. All agree the chain of cus-
tody was imperfect, as Oﬃcer Davies left the phone on his
desk overnight. But perfection is not the proper measure. The
imperfection the law tolerates here comes from the fact that,
at all times, the phone remained secured within the FBI’s of-
ﬁce. In these circumstances, the law aﬀords a presumption
that the integrity of the phone remained intact, that nobody
tampered with it. Dewitt oﬀers no evidence to the contrary
and any speculation could have been considered by the jury
in assigning weight to the evidence.
                               IV
    Finally, we reach Dewitt’s challenge to his sentence. The
district court determined that Dewitt’s advisory guidelines
range was 70 years’ imprisonment. At sentencing, the court
considered Dewitt’s mental inﬁrmities, abusive childhood,
and other mitigating factors. It also noted that below-guide-
lines sentences are not uncommon for child pornography of-
fenders. The court found that these circumstances warranted
a downward variance and in the end sentenced Dewitt to 30
years.
    We employ a two-step process in reviewing a sentence. We
ﬁrst review the sentence for procedural soundness and, if we
ﬁnd no error, assess its substantive reasonableness. See United
States v. Jackson, 547 F.3d 786, 792 (7th Cir. 2008). Here Dewitt
challenged only the substantive reasonableness of his 30-year
term of imprisonment. The law is clear, however, that “[a] be-
low-guidelines sentence is ‘presumptively reasonable against
an attack by a defendant claiming that the sentence is too
high.’” United States v. Solomon, 892 F.3d 273, 278 (7th Cir.
2018).
10                                                 No. 19-1295

    We see no inﬁrmity with Dewitt’s sentence. Contrary to
Dewitt’s reading of the sentencing transcript, it is clear the
district judge gave careful and suﬃcient mitigating consider-
ation to Dewitt’s mental inﬁrmities. And the ultimate sen-
tence of 30 years was less than half the low-end of the advi-
sory range. We have never held a below-guidelines sentence
to be unreasonably high. See United States v. George, 403 F.3d
470, 473 (7th Cir. 2005) (“It is hard to conceive of below range
sentences that would be unreasonably high.”). This case does
not warrant being the ﬁrst.
     For these reasons, we AFFIRM.
