An Alaska-based FBI agent trained to detect sharing of child pornography over the internet testified that he could’ve obtained child pornography from a Wrangell doctor’s house on at least four occasions last year.

Special Agent Anthony Peterson took the witness stand on Thursday in the trial of Greg Salard that is now underway in U.S. District Court in Juneau. Salard has been charged with felony receipt, possession and distribution of child pornography.

He was arrested at his home in Wrangell last October after Peterson used a law enforcement version of a peer-to-peer (P2P) sharing program to access a video file of child pornography on a laptop computer belonging to Salard. Peterson says he was able to pinpoint the computer’s location at Salard’s house after tracing the Internet Protocol or IP address of the P2P program that he used.

Peterson testified that he decided to execute a search warrant after observing Salard offer to share a child pornography video through the Ares P2P program. When Peterson and another agent arrived at the house and found Salard’s laptop, they discovered that a wiping program called CCleaner was already running. Most computer files leave remnants and can still be reconstructed even after they’ve been deleted, but CCleaner can wipe the hard drive clean and remove any evidence of a deleted file.

Peterson also described three other occasions between May and October of last year in which he could see other files of child porn or download a partial file from Salard’s laptop.

Peterson testified for the prosecution for most of the hearing. Later, he was questioned about the search for evidence of downloaded child pornography, detailing files that were recently viewed or deleted, and the use of various other P2P programs on Salard’s Alienware laptop.

Peterson says he found evidence of all three activities after making a copy of the hard drive and using various tools or forensic programs to view individual data files that are buried deep within the operating system.

It’s been an education for most of the fourteen jurors who, during jury selection on Monday, admitted that they have limited technical experience and may only use a computer for shopping, Facebook, blogging or gaming.

Under cross examination, defense attorney Cara McNamara later went after Peterson’s perceived inexperience by quizzing him about the various routines of a computer’s operating system and file deletion routines.

Earlier in the day, with the jury out of the courtroom, attorneys for both sides argued for admission as evidence a list of just over 6oo pornography files found on Salard’s laptop computer. Salard’s defense objected and said it should be limited to only 83 files that were positively identified as child pornography and not the other 525 files of other forms of pornography.