Opinion for the Court filed by Circuit Judge ROGERS.
Two main issues predominate in this appeal of a criminal conviction for interstate transportation of a minor with intent to engage in criminal sexual activity and possession of photographs of minors engaged in sexually explicit conduct. The first issue is whether the district court abused its discretion in admitting other-acts evidence and expert testimony; the second involves the standard of proof to be applied at sentencing. Kenneth Keith Long appeals his conviction on the ground that the district court admitted extrinsic evidence of Long’s sexual activity with *659 young adults and of his possession of photographs depicting unidentified individuals for no proper reason under Federal Rule of Evidence 404(b), thereby creating a prejudicial risk of misuse of the evidence to show propensity under Federal Rule of Evidence 403. Long also contends that the district court erred by permitting the government to introduce expert testimony profiling “preferential sex offenders” in violation of Federal Rules of Evidence 404(a) and 403. Long’s challenge to his sentence arises because the district court’s application of the cross references in §§ 2Gl.l(c)(l) and 2G2.4(c)(l) of the Sentencing Guidelines resulted in an eight-level increase in his offense level. He contends that this increase required clear and convincing proof (of which, he claims, there is none) to show that his offenses included conduct that had as its purpose the production of sexually explicit depictions of the minors, as required by the cross references.
Under Rules 401, 403, and 404, a defendant is entitled to the considered judgment of the district court before evidence of uncharged conduct is admitted. In the main, these are rules of admission, subject to limited exceptions to be applied in the exercise of the district court’s discretion. The record makes clear that Long received his due. The district court’s examination of the government’s proffered evidence was sensitive to the prejudicial effect of which Long complains on appeal, while remaining responsive to the government’s need to rebut Long’s defense and present its case,
see Old Chief v. United States,
I.
The evidence at trial revealed that Long, a Baptist minister and substitute teacher, became acquainted through those positions with a number of minor boys between thirteen and sixteen years of age. Six of the boys were the victims underlying the charges in the indictment. According to the six boys’ trial testimony, Long engaged in a pattern of conduct that resulted in sexual contact with them, often taking sexually explicit photographs. In addition to the six boys, the government called two non-minor, males, “FM” and “AG,” ages sixteen and nineteen at the time of their interaction with Long, who testified that Long had engaged in similar patterns of conduct resulting in sexual activity with them and had taken sexually explicit photographs. The government also introduced a large number of photographs— over 250 — found in Long’s apartment, showing the minor victims and other young males in sexually explicit poses. Finally, the government presented Federal Bureau of Investigation Agent Kenneth Lanning, who testified as an expert “in the field of sexual exploitation of children,” including “the typology, identification, characteristics, and strategies of sexual offenders, in particular preferential sexual offenders,” as well as “the characteristics and behavior of child victims of sexual abuse.”
Long was tried on a seven-count indictment charging four counts of interstate transportation of a minor with the intent to engage in criminal sexual activity, 18 U.S.C. § 2423(a) (2000), and two counts of possession of visual depictions of minors engaged in sexually explicit conduct, 18 U.S.C. § 2252(a)(4)(B) (2000). The gov- *660 eminent dismissed a seventh count, for sexual exploitation of a child, during trial. The jury returned a split verdict: it found Long guilty of two counts of interstate transportation and two counts of possession of child pornography but not guilty of one count of interstate transportation (of “JLG”); it deadlocked on another count of interstate transportation (of “EB”), which the government later dismissed. After denying Long’s motion for a new trial, the district court sentenced Long to 360 months imprisonment followed by three years supervised release, imposed a fine and assessment, and recommended mental health counseling under the Bureau of Prisons’ sex offender treatment program.
II.
On appeal, Long contends that the district court abused its discretion in admitting two types of evidence. First, Long contends that the district court erred in admitting the testimony of FM and AG, who were not minors under the applicable statute at the time of their acquaintances with Long. Acknowledging that FM’s testimony was “prejudicial,” the district court ruled the testimony was admissible to show intent, modus operandi, and absence of mistake or accident. Similarly, the court ruled that AG’s testimony was admissible and instructed the jury that it could consider AG’s testimony only to determine whether Long acted with a criminal intent with respect to the charges in the indictment, engaged in a scheme or plan, used a similar modus operandi, had a motive to commit the charged crimes, or acted knowingly. The court cautioned that the jury could not consider either man’s testimony to find that Long had a bad character or criminal propensity. Long contends that testimony about his lawful acts was not relevant under Federal Rule of Evidence 401 to establishing criminal intent, modus operandi, or a common plan or scheme. He further contends that the testimony was inadmissible character evidence under Rule 404(b) and should have been excluded under Rule 403 because its unfair prejudicial effect substantially outweighed its probative value.
Our review of the district court’s Rule 404(b) rulings is for abuse of discretion,
United States v. Bowie,
Under Rule 401, evidence is relevant if it has “any tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence.” Fed.R.Evid. 401. Not all relevant evidence, however, is admissible. Rule 404(b) provides that “[e]vidence of other crimes, wrongs, or acts is not admissible to prove the character of a person in order to show action in conformity therewith.” Fed.R.Evid. 404(b). But the rule stipulates that such evidence “may ... be admissible for other purposes, such as proof of motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake or accident....”
Id.
Under the law of this circuit, “Rule 404(b) is a rule of inclusion rather than exclusion,”
Bowie,
Among the several grounds for admitting the testimony of FM and AG, the district court found that it was probative of Long’s intent to engage in criminal sexual conduct with the six minor victims. Long contends that this was not a proper ground for admission because there is an incon-gruence between Long’s intent to engage in lawful sexual conduct with males over the age of sixteen and his alleged intent to engage in unlawful sexual conduct with minor boys. Extrinsic act evidence is admissible under the intent theory, he maintains, only if the intent underlying the extrinsic act is the same illegal intent required for the charged act.
Evidence of a similar act must meet a threshold level of similarity in order to be admissible to prove intent,
see Jankins v. TDC Mgmt. Corp.,
The chief theory of Long’s defense was that the six alleged minor victims had fabricated their tale of sexual abuse. Long thus denied not that he had a close relationship with the boys, but rather that he had ever engaged in sexual activity with them. The testimony of FM and AG was relevant to show Long engaged in a “pattern of operation,” 2 Weinstein’s Federal Evidence § 404.22[l][a], that lends credence to the minors’ assertions that in their cases as well the seemingly innocent behavior culminated in sexual contact. The manner in which Long developed a relationship with the minor boys was strikingly similar to the way in which he ingratiated himself to FM and AG. Like the minor victims, FM was a special education student, and Long asked FM to give Long “candy” whenever Long wanted oral sex, in exchange for which Long promised to buy FM sneakers and other gifts. Long also sought to videotape and take photographs of FM masturbating. AG, too, was a special education student for whom Long was a substitute teacher, and AG, too, received offers of gifts from Long in addition to overt sexual advances. As he had done with the six minors, Long recruited FM and AG to join the Alpha Phi Gents fraternity, which both witnesses understood would (and, in FM’s case, did) involve sexual acts. In a similar context, the Seventh Circuit held that “classic modus operandi evidence used to respond to the
*662
defense argument that [the defendant] had only innocent intentions” with respect to the young male victim was “highly probative of intent.”
United States v. Romero,
Long contends, however, that even if the testimony of FM and AG was relevant for a purpose unrelated to criminal propensity, its “slight probative value was substantially outweighed by the unfair risk that the jury would infer that Long had a propensity to engage in sexual activities with teenagers — be they minors or young adults.” Appellant’s Br. at 20. Under Rule 403, relevant evidence “may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by ... needless presentation of cumulative evidence.” Fed. R.Evid. 403. This court has observed that “Rule 403 contemplates the thoughtful consideration of the trial court and leaves the admission of evidence to the sound discretion of the trial judge.”
United States v. Boney,
The district court concluded that the significant probative value of FM’s and AG’s testimony was “not substantially outweighed by the danger of unfair prejudice or confusion of the issues or misleading the jury” in light of instructions that the court would give to the jury.
See Crowder II,
Similar concerns underlie Long’s second evidentiary objection to the admis *663 sion of “voluminous” photographic evidence. Long challenges the admission of photographs and negatives that were not part of the child pornography charges in counts six and seven but instead were seized from Long’s home after his arrest. He contends that evidence of his possession of these uncharged photographs was irrelevant because the photographs were not proven to be depictions of minors, and his possession was therefore lawful. Hence, he maintains, the substantial number of uncharged, sexually explicit and suggestive photographs only provided bad character evidence and served no proper purpose under Rule 404(b) inasmuch as “evidence of lawful possession of certain items is not admissible under Rule 404(b) to prove unlawful possession of similar items.” Appellant’s Br. at 25.
The district court did not allow the government to offer into evidence all 301 of its proffered photographs and negatives. Rather, over the course of three days, the court examined each piece of evidence and spent hours "with counsel in chambers reviewing the photographs in addition to hearing arguments in court regarding their admissibility. The district court then limited the government to introducing photographs that: (1) corroborate the government witnesses’ testimony of certain events and activity; (2) demonstrate the minor boys’ relationship with Long; (3) rebut Long’s defense that the minor victims had fabricated the allegations of sexual abuse and that he did not possess the charged photographs; or (4) show modus operandi. The court also instructed the jury that it could not consider the photographic evidence to conclude that Long had a “bad character.” With these limitations, the district court concluded that admission of uncharged photographs in Long’s possession would not show mere propensity to collect child pornography but were admissible for legitimate Rule 404(b) purposes. The uncharged photographic evidence was relevant in light of Long’s denial of the possession of the child pornography charged in counts six and seven of the indictment: many of the charged photographs and negatives were found in packets and envelopes with the uncharged photographs that the court allowed the government to introduce into evidence, and Long’s fingerprints also were found on some of the uncharged photographs.
It hardly can be denied that “in cases where a defendant is charged with unlawful possession of something, evidence that he possessed the same or similar things at other times is often quite relevant to his knowledge and intent with regard to the crime charged.”
United States v. King,
Long’s reliance on
Guam v. Shymanovitz,
Of course, evidence that is admissible under Rule 404(b) may still be excluded under Rule 403 “if its probative value is substantially outweighed by the danger of unfair prejudice.... ” Fed.R.Evid. 403. Long contends that “[t]he sheer volume of the extrinsic photographic evidence contributed to its prejudicial impact” and that “the devastating effect of the hundreds of photos of mostly unidentified young males substantially outweighed their marginal probative value under Rule 403.” Appellant’s Br. at 28. In Long’s view, the district court “should have severely restricted the number of photographs of young males viewed by the jury and excluded virtually all of the uncharged sexually explicit or suggestive ones.” Appellant’s Br. at 29. At oral argument in this court, the government acknowledged that “a lot” of photographs were introduced into evidence but contended that the evidence was necessary to rebut Long’s defense of lack of possession of the charged items.
Under Rule 403, the district court has discretion to exclude evidence that is unfairly prejudicial where its effect is merely cumulative. Fed.R.Evid. 403;
see, e.g., United States v. Rose,
The district court reviewed
in camera
every photograph that the government sought to introduce into evidence and heard argument on the admissibility of
*665
each. Outside the presence of the jury, the court identified virtually every photograph and explained its reasons for admitting or excluding the evidence. For instance, the court described a number of photographs that featured nude or partially nude males of unidentified ages, often sexually aroused or masturbating. The court ruled that the government would not be allowed to introduce these photographs into evidence if they contained no other relevant information that connected Long to the charged offenses. While undertaking this examination, the court was mindful of the possibility that the large number of photographs, taken together, might have an unfair prejudicial effect. It explained that “there is a continuum of explicitness,” and that, “to the extent that the quantity of pictures ... may together create ... unfair prejudice,” the court was inclined to exclude the most explicit and least probative photographs. This is the type of “thoughtful consideration,”
Boney,
III.
Long also contends that the district court erred in admitting the expert testimony of FBI Agent Kenneth Lanning. The district court allowed Lanning to testify “as an expert concerning sexual exploitation of children, including the typology, identification, characteristics and strategies of a sexual offender, particularly preferential sex offenders, and the characteristics and behavior of child victims of sexual abuse.” Long does not challenge Lan-ning’s testimony as improper under the Rules of Evidence that generally govern expert testimony, Fed.R.Evid. 702-06, or the Supreme Court’s decisions in
Daubert v. Merrell Dow Pharmaceuticals,
Lanning’s testimony focused on the behavior of a class of criminals he termed “preferential sex offenders,” whose sex offenses are characterized by “paraphilia,” or “an attraction to or intense fantasies ... involving certain elements.” He opined that “very often part of their preference is the age and gender of their victim,” and that “their primary motivation is, in fact, sexual gratification.” Lanning identified three patterns of behavior within the general class of preferential sex offenders. Among these patterns of behavior is the “seduction process,” through which the sex offender uses attention, kindness, gifts, and money to lower his or her victims’ inhibitions. During this process, the sex offender often will use alcohol, drugs, and pornography to arouse the victims and to lower further their inhibitions. Lanning also opined that these offenders often have strong interpersonal skills and occupy positions of authority, such as a school teacher or minister, and also are often adept at identifying victims who are weak and vulnerable, such as chil *666 dren whose family life is dysfunctional. Lanning added that sex offenders often photograph their victims, and he also offered insight into the reasons why children who are victimized by a sex offender may remain in the offender’s presence.
Rule 404(a) provides that “[e]vidence of a person’s character or a trait of character is not admissible for the purpose of proving action in conformity therewith on a particular occasion,” except in specified circumstances. Fed.R.Evid. 404(a). According to Long, Lanning’s testimony contravened this rule because it tended to show that Long acted in conformity with the characteristics of a preferential sex offender in committing the charged offenses. Although Long acknowledges that Lanning did not explicitly testify that Long exhibited the characteristics of a preferential sex offender, he contends that, to the extent the expert testimony mirrored the government’s case against him, it was analogous to the improper use of a criminal profile as substantive evidence.
“Courts have condemned the use of profiles as substantive evidence of guilt,”
United States v. McDonald,
The admission of Lanning’s testimony has been approved by the two circuits to have considered it. In
United States v. Romero,
As noted, this court has generally permitted expert testimony regarding the mo-dus operandi of a certain type of criminal offender.
See, e.g., Watson,
Again, Long contends that even if the expert testimony was relevant and admissible under Rule 404(a), it was so inherently prejudicial that the district court should have excluded it under Rule 403. The Eleventh Circuit rejected this objection to Lanning’s testimony in
Cross,
observing that the testimony’s “considerable probative value” was not outweighed by any possible prejudicial effect.
Cross,
For much the same reasons as in
Cross
and
Anderson,
Long’s Rule 403 objection fails: Lanning’s testimony was offered for a permissible purpose, namely to identify the behavior and actions of child molesters and explain their modus operandi, the prosecution adduced considerable other evidence of Long’s pedophilia, and the jury was instructed that the weight to be given to Lanning’s testimony was for the jurors to determine.
See Cross,
IY.
Long’s challenges to the sufficiency of the evidence of the interstate transportation of one of the minor boys (“JS”) and the possession of photographic negatives require only brief response.
Viewing the evidence, as we must, in the light most favorable to the government,
United States v. Morris,
We also hold that there was sufficient evidence to sustain Long’s conviction on count seven for possession of photographic negatives of child pornography.
See Morris,
y.
Long’s challenge to his sentence focuses on the standard of proof. He contends that the district court erred in enhancing Long’s base offense level by eight levels on the basis of acquitted conduct without finding by clear and convincing evidence that Long engaged in the relevant conduct. This court reviews a sentencing court’s factual determinations for clear error,
United States v. Jackson,
Section 2G1.1 of the Sentencing Guidelines applies to convictions for interstate transportation of minors with the intent to engage in criminal sexual activity. United States Sentencing Commission Guidelines Manual (“U.S.S.G.”) § 2G1.1 (2000). A cross reference provides, however, that “[i]f the offense involved causing, transporting, permitting, or offering ... a person less than 18 years of age to engage in sexually explicit conduct for the purpose of producing a visual depiction of such conduct,” the sentencing court is to apply Guideline § 2G2.1. U.S.S.G. § 2Gl.l(c)(l).
*670
The district court found that the cross reference applied and treated § 2G2.1 as the controlling Guideline provision.
United States v. Long,
Long acknowledges that the preponderance of the evidence standard ordinarily applies to sentencing determinations.
McMillan v. Pennsylvania,
The Supreme Court has noted “a divergence of opinion among the Circuits as to whether, in extreme circumstances, relevant conduct that would dramatically increase the sentence must be based on clear and convincing evidence.”
Watts,
The Supreme Court has “held that application of the preponderance standard at sentencing generally satisfies due process.”
Watts,
Lower courts, however, have recognized that “legal rules — even rules that function perfectly well in familiar contexts when stated in categorical terms — cannot always be applied in extreme situations.”
Kikumura,
Because the district court applied the correct standard of proof at sentencing, there is no merit to Long’s challenge to the findings that Long’s “purpose” in transporting the minors more likely than not was to create child pornography, thereby justifying application of the § 2Gl.l(c)(l) cross reference. There was ample evidence that Long had taken sexu
*672
ally explicit photographs of each of the six minor victims, and the testimony of the victims, and Lanning, supports the finding that Long’s transportation of the minors was motivated at least in part by a desire to create these visual depictions.
Long,
Accordingly, we hold that: there was no abuse of discretion in the district court’s evidentiary rulings under Rules 401, 408, and 404(a) and (b); there was sufficient evidence for conviction of the charges in counts six and seven; and there was no error at sentencing, and we affirm the judgment of conviction.
