For the investigators seeking to identify child pornography victims, every little bit of information – from the designer of the clothing worn in the pictures to the type of wallpaper in the background – helps, law enforcement experts told ABCNEWS.com.
"We look at the house and the building and determine whether [the tape was filmed] outside," said Detective Constable Bill McGarry, an image analyst at the child exploitation section of the sex crimes unit at the Toronto Police Department. "We look for anything that will point us to a geographical location and also try isolate objects in the background – furniture, bedding, clothing – things that we can trace to certain manufacturers. It's a lead that can make all the difference."
These clues, said McGarry, are vital to cases like the one in Nye County, Nev., where authorities are searching for the second girl seen on a videotape that depicts a man performing sex acts on a young girl. The tape was turned over to authorities by Darren Tuck, who said he found the tape in the desert and has since been arrested on charges of possession and promoting child pornography.
While one girl seen on the tape has been located and is safe, according to the Nye County Sheriff's Office, the second, said to be either 4 or 5 years old when the tape was made several years ago, hasn't been identified. Her name is believed to be Madison, police said, based on what they heard on the tape.
[UPDATE: Police said late Friday, Sept. 28, that the younger girl in the videotape was found and "safe."]
At a press conference Friday, the Nye County sheriff's office identified Chester Arthur Stiles, 34, as a "person of interest" in the case. Stiles is wanted on both state and federal warrants for sexual assault and lewdness with a minor.
Less than 1 percent of children who appear in sex tapes are found each year, according to Interpol statistics. That means sex crime investigators are often left with no choice other than to dig deeper into the minute details caught on tape in hopes of pinpointing both the victimized children and their assailants.
With so many videos to sift through, deciphering the country of origin can be a challenge in and of itself. McGarry will meet with a group of international investigators on a secure Web site to trade information about particular videos and victims. Once the location of the video is determined, an investigator from that region will take over the case. Often, though, investigators will collaborate no matter where they are located to close a particular case.
McGarry, who said he has been in contact with the investigators handling the Nevada case, said that determining whether the video of the two girls was taped at the same time or cut and edited together will be helpful to finding the victim.
VHS tapes, unlike video streamed over the Internet or recorded on DVDs, have less of the embedded data that can tell investigators the date the video was shot, said McGarry. If the tape wasn't edited, the fact that the investigators already found one of the victims could be a huge help to finding the second missing girl.
But without much detail coming from the VHS itself, investigators use other techniques to look for clues.