FORENSIC ANALYSIS

Clues Buried in Sounds and Images

02/12/10 - The 14 videotapes arrived on Peter Smith’s desk individually wrapped in plain manila envelopes. They had been sent by a special agent in our Phoenix office who wanted them analyzed after heavy rains exposed the buried cache in a yawning 35-foot-deep hole in the ground. A man who found the tapes saw the contents of one of them and quickly called the police, who in turn called us.

The tapes were in bad shape, but that’s nothing new to Smith, whose job it is to repair and recover damaged media so the contents can aid investigators. Smith is one of 26 examiners who work in the FBI’s Digital Evidence Laboratory’s Forensic Audio, Video, and Image Analysis Unit. Based in Quantico, Virginia, the unit gets requests from all 56 field offices and our overseas offices, or legal attachés.

“When I got them, they were caked with mud,” said Smith, a specialist in video reconstruction. Like his colleagues, he’s worked on tapes in much worse condition—unspooled, soaked in jet fuel, stretched, cut, or partially demagnetized. Every case is different.

“You have to assess each case in order to get it back into playable condition,” Smith said. In this case, that meant unspooling the tightly wound tapes, rinsing away the mud, and carefully drying them. The tapes were put on new spools and into new housings. Duplicates were recorded when the restored tapes were played. The original and new recordings were then sent back to Phoenix so investigators could move forward on the case.

Last year, the unit closed 610 examination requests—274 on audio and 336 on video and still images. On any given day, examiners are looking for even the smallest clues that could aid in a case.

In the 2007 case of the unearthed tapes, the recovered material revealed a man engaging in sexual activity with minor girls, one believed to be 5 or 6 years old. The tapes were decades old and recorded in a format that predates VHS. As Smith reconstructed the tapes, he found a key piece of evidence—one of the girls said the name of the man appearing with her on the video. Smith contacted the FBI case agent in Phoenix, who ran a check of motor vehicle licenses, which led him to an 81-year-old man who managed the property where the tapes came to light. He was quickly arrested.

Like video, audio and still images contain a bounty of potential clues. Examiners look for patterns and textures in clothes or a suspect’s distinctive physical features. Photogrammetry can reveal a suspect’s height or the length of a gun’s barrel. In many cases, with the proliferation of sophisticated photo-editing software, examiners can determine if images have been digitally manipulated, as is sometimes the defense claim in child pornography cases.

“It’s enabled us to hone our skills as far as recognizing real versus fake,” said Dr. Richard W. Vorder Bruegge, one of our image examiners and a leader in the field of forensic analysis.

The Digital Evidence Laboratory, part of our Operational Technology Division, has played a key role in a wide variety of high-profile cases, including the 9/11 probe, the Enron investigation, and the 2004 murder of 11-year-old Carlie Brucia, a case that relied heavily on analysis of grainy surveillance video showing her abductor leading her away from a Florida car wash.

For examiners working on the periphery of so many cases, it’s particularly satisfying when their forensic analysis plays a central role in an investigation. In the buried tapes case, the discovery of the man’s identity led to a search of his home—and more sex tapes. The man eventually pled guilty to child pornography charges and was sentenced in 2008 to more than six years in prison.

“This is one of the more rewarding cases,” Smith said. “To take a hunk of garbage and turn it into usable evidence—that’s very rewarding.”