MURPHY, Circuit Judge.

I. INTRODUCTION

[p. 1] The appellant, Jeffrey Tucker, was convicted of one count of possession of child pornography, 18 U.S.C. § 2252A(a)(5)(B), and sentenced to sixty months' imprisonment. [n. 1] He appeals his conviction on numerous grounds. We have jurisdiction under 28 U.S.C. § 1291 and affirm.

1. The version of § 2252A(a)(5)(B) under which Tucker was convicted criminalized knowing possession of material "that contains 3 or more images of child pornography." After Tucker committed the crime, § 2252A(a)(5)(B) was amended to criminalize knowing possession of material containing "an" image of child pornography. Throughout this opinion, citations to § 2252A(a)(5)(B) are to the older version under which Tucker was charged and convicted.

Tucker was convicted in 1990 in Utah state court for sexually abusing a child. He was paroled by the Utah Department of Corrections in 1996. As part of his parole agreement, Tucker agreed to "permit agents of Adult Probation and Parole to search my person, residence, vehicle or any other property under my control, without a warrant, at any time, day or night, upon reasonable suspicion to ensure compliance with the conditions of my parole." He further agreed to "[n]ot view or have in my possession any material exploiting children or depicting unconsensual sex acts or acts involving force or violence." In another part of the agreement, he agreed to "[h]ave no contact with children under age 18 without the supervision of an adult who is aware of my sexual deviancy." Finally, he agreed to "obey all state, federal, and municipal laws." In June 1998, Tucker was still on parole and subject to the parole agreement.

On June 10, 1998, Corina Groneman, a former employee of the United States Bureau of Reclamation ("Reclamation") spoke over the telephone with Officer Ryan Atack of the Salt Lake City Police Department about Tucker. Groneman told Atack that a friend ("friend 1"), who wished to remain anonymous, had received information that Tucker was viewing child pornography on his computer and had contacted a child. According to friend 1, a friend of his ("friend 2"), who also wished to remain anonymous, visited Tucker at his residence. Friend 2 worked at Reclamation, as did friend 1, Tucker, and Groneman. [n. 2] Tucker showed friend 2 child pornography on his computer and informed her that he had met a young girl and might try to arrange another meeting with the child. Groneman never informed Atack of the identity of either friend 1 or friend 2, but she did identify herself and told him she was an employee of the U.S. Attorney's office.

2. Tucker began working at Reclamation after Groneman left to work at the U.S. Attorney's office.

On the evening of June 11, 1998, England, Bartell, Atack, and several Salt Lake City police officers searched Tucker's residence. England and Bartell approached the apartment from the front. The screen door on the apartment was closed but the main door was open. Before he entered, England saw Tucker near a computer. England and Bartell entered the apartment. Upon entry, England ordered Tucker away from the computer. Immediately, Detective Rick Gruber, a police officer with expertise in computer crimes, approached the computer. Before taking control of the computer, he noticed that it was connected to the Internet and that Tucker had been visiting a newsgroup [n. 3] labeled "alt.sex.preteen." Gruber ran software on Tucker's computer designed to prevent alteration of the hard drive. He then discovered that a large number of files recently had been deleted from Tucker's hard drive. Gruber ran another program that allowed him to view deleted files, but none of the deleted files he viewed contained pornography. In his investigation of Tucker's Web browser history, [n. 4] however, he noticed that Tucker had visited other newsgroups whose names suggested they contained child pornography. Gruber informed Tucker that technology existed to recover the deleted files. Parole Agent Bartell then asked Tucker "What are we going to find?" Tucker responded, "There's some stuff on there that's going to cause me problems." Bartell ordered the computer seized.

3. A newsgroup is a location on the Internet which, as Detective Gruber testified, "is analogous to a bulletin board where people post messages and they're able to reply, and they're also able to exchange data, exchange documents and images."

4. The World Wide Web is one form of communication available over the Internet. It allows computer users "to search for and retrieve information stored in remote computers, as well as, in some cases, to communicate back to designated sites." Reno v. Am. Civil Liberties Union, 521 U.S. 844, 852 (1997). The information is stored in the form of Web "pages." See id. "Web pages frequently contain information and sometimes allow the viewer to communicate with the page's (or 'site's') author. They generally also contain 'links' to other documents created by that site's author or to other (generally) related sites." Id. A Web browser is computer software that allows a user to view Web pages. Tucker used two different Web browsers, Microsoft Internet Explorer and Netscape Navigator. Each Web browser keeps a history, or list, of Web pages recently visited by the user.

5. The Board revoked Tucker's parole nearly two years later on February 8, 2000.

6. Hooper testified that ".jpg" files are a type of image file. Other types include .gif, .bmp, and .art files.
7. The government's witness, Senior Special Agent Don Daufenbach of the United States Customs Service, testified at trial that a "cache file" is a location on a computer's hard drive that contains "a collection of data images typically that have been gleaned from your travels around the Internet." Daufenbach explained that upon visiting a Web page, a Web browser immediately caches or saves the images on that page in the cache file. If a user selects an image on a Web page in order to enlarge the image, the larger image is also cached. The Web browser automatically caches such images; no act is required of the user. The purpose of caching is to allow already-visited pages to forego the necessity of loading pictures and thus allow visits to these pages to be processed much faster.
8. The recycle bin is a location on the computer in which a user places files to be deleted.

[p. 3] The district court also rejected Tucker's argument that his parole agreement did not authorize seizure of his computer. The district court acknowledged that the parole agreement did not mention seizures but concluded that "seizure of contraband or evidence garnered from a valid parole search is clearly implicit in any parole agreement." Tucker's final Fourth Amendment argument was that the July 28 forensic examination of his computer was not a valid parole search because Tucker was already in custody and the search could not therefore have any parole purpose. The district court rejected the argument, reasoning that Tucker's parole was not yet revoked when Hooper conducted the forensic examination and the officers "had an incentive to compile evidence that he had violated his parole for use at the [revocation] hearing."

After a bench trial, the district court found the defendant guilty. See United States v. Tucker, 150 F.Supp.2d 1263, 1270 (D.Utah 2001). It found that Tucker visited Web sites that displayed child pornography as thumbnail images. See id. at 1265. Tucker would often select thumbnail images to enlarge them. See id. The district court found that upon visiting a site displaying thumbnail images or upon selecting a thumbnail for enlargement, the images were automatically cached on Tucker's hard drive. See id. The district court found that Tucker had admitted that he routinely accessed the cached images on his hard drive and deleted them after an Internet session. See id.

The district court concluded that Tucker possessed child pornography under the meaning of 18 U.S.C. § 2252A(a)(5)(B) because he had control over the images cached on his hard drive. See id. at 1267. The court reasoned that Tucker's habit of manually deleting images from the cache files established that he exercised control over them. See id. The district court also rejected Tucker's argument that since the Web browsers automatically cached image files without his input, he did not voluntarily possess the images. The district court reasoned that Tucker visited Web sites for the purpose of viewing child pornography, and that "[t]he images would not have been saved to his cache file had Tucker not volitionally reached out for them." Id. at 1268. Finally, the district court concluded that Tucker's possession was knowing, since he purposefully visited Web sites containing child pornography knowing that the images would be stored on his computer's hard drive. See id. at 1269.

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IV. KNOWING POSSESSION OF CHILD PORNOGRAPHY

[p. 8] Tucker contends the evidence that he knowingly possessed child pornography was insufficient to support his conviction. We review the sufficiency of the evidence supporting a guilty verdict de novo. See United States v. Carter, 130 F.3d 1432, 1439 (10th Cir.1997). We will not disturb the verdict unless no rational trier of fact could have found the defendant guilty. See id. This court "must view the evidence and the reasonable inferences to be drawn therefrom in the light most favorable to the government." United States v. Haslip, 160 F.3d 649, 652 (10th Cir.1998).

Tucker maintains that he did not possess child pornography but merely viewed it on his Web browser. [n. 15] He concedes, however, that he knew that when he visited a Web page, the images on the Web page would be sent to his browser cache file and thus saved on his hard drive. Yet, Tucker contends that he did not desire the images to be saved on his hard drive and deleted the images from his cache file after each computer session. There is no merit to this argument.

15. Tucker makes a related argument that the images he viewed on his Web browser were not child pornography under the statute because they were not "stored" on his computer. 18 U.S.C. § 2252A(a)(5)(B) only criminalizes possession of "child pornography." Child pornography is defined in 18 U.S.C. § 2256(8) to be "any visual depiction, including ... computer or computer-generated image or picture, ... of sexually explicit conduct" engaged in by minors. "Visual depiction" in turn is defined in § 2256(5) to "include[ ] undeveloped film and videotape, and data stored on computer disk ... which is capable of conversion into a visual image." (emphasis added). Thus, Tucker argues the images found on his computer cannot be considered a visual depiction because they were not data actually stored on his computer but only temporarily displayed on his computer monitor. The argument is not convincing. Section 2256 does not require a visual depiction to be stored data. Rather, the definition merely says that one type of visual depiction is data stored on computer. See id. § 2256(5) (providing that the definition of visual depiction "includes ... data stored on a computer disk" (emphasis added)). Even if the definition required that a visual depiction be data stored on a computer, the images Tucker viewed were contemporaneously stored on his hard drive when his Web browser saved the images to a cache file.

knowingly possesses any book, magazine, periodical, film, videotape, computer disk, or any other material that contains 3 or more images of child pornography that has been ... transported in interstate ... commerce ... shall be punished.

Customs Agent Daufenbach testified that an individual could access an image in a cache file, attach it to an email, post it to a newsgroup, place it on a Web site, or print a hard copy. He stated, "Just like as with any other data file, you could do almost anything with it." Agent Hooper similarly testified that an individual could "view [an image in the cache]. He could rename it. He could copy it to a floppy disk. He could email it to somebody. He could modify the file.... Anything he could do with any other file he could do with these files." This unrebutted testimony conclusively demonstrates Tucker had control over images stored in his cache and thus possessed them.

Tucker argues, however, that he did not voluntarily cache the files. Rather, he maintains, his Web browser "sav[ed] the images against his will." Tucker likens his situation to the classic case of Martin v. State, in which the defendant was charged with appearing drunk in public after involuntarily being carried into public by the police. See 17 So.2d 427, 427 (Ala.Ct.App.1944). The Martin court held that voluntariness was a necessary element to the crime. See id. The analogy is not apt. The defendant in Martin did not drink with the understanding that he would be taken out in public. Tucker, however, intentionally sought out and viewed child pornography knowing that the images would be saved on his computer. Tucker may have wished that his Web browser did not automatically cache viewed images on his computer's hard drive, but he concedes he knew the Web browser was doing so. Tucker continued to view child pornography knowing that the pornography was being saved, if only temporarily, on his computer. In such circumstances, his possession was voluntary. Since he knew his browser cached the image files, each time he intentionally sought out and viewed child pornography with his Web browser he knowingly acquired and possessed the images. [n. 16]

16. We offer no opinion on whether the mere viewing of child pornography on the Internet, absent caching or otherwise saving the image, would meet the statutory definition of possession. We likewise do not address the question whether an individual could be found guilty of knowingly possessing child pornography if he viewed such images over the Internet but was ignorant of the fact that his Web browser cached such images.

[p. 9] Tucker's conviction is AFFIRMED. [n. 17]

17. Tucker contends that a conviction under § 2252A(a)(5)(B) for simply viewing child pornography runs afoul of the First, Fifth, and Eighth Amendments. Though not entirely clear from the briefs, Tucker's contention appears to be an as-applied challenge to § 2252A(a)(5)(B). Assuming for the sake of argument that the criminalization of the viewing of child pornography is unconstitutional, Tucker's challenge must fail because he was not convicted for simply viewing child pornography, but for viewing images of child pornography with the knowledge that the images were thereby saved on his computer. To the extent Tucker presents a facial overbreadth challenge, the briefs do not present a legal argument supported by citation to relevant authority. We will thus not consider the argument.