*1 Before F LAUM , S YKES , and S CUDDER , Circuit Judges . S CUDDER , 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 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 d aughter, 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.
In time the FBI arrested Dewitt and sei zed 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 the verdict on the distribution charge because a rational jury could find beyond a re asonable 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
,
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
,
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 *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
,
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.”
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, gu ardians, 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, a nd someone who has reached the age of 18. That a particular *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,
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 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 bei ng 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
,
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 s ubstantive reasonableness. See
United
States v. Jackson
,
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.
