Each week, about 100,000 sexually explicit images of children arrive on CDs or portable disk drives at Michelle Collins' office.
They are sent by police and prosecutors who hope Collins and her 11 analysts at the National Center for Missing and Exploited Children can verify that the graphic pictures are real, not computer-generated. When they can't, officials sometimes turn to outside experts.
All this is being done — at an annual cost in the millions of dollars collectively in child-pornography cases alone — as software like Photoshop makes it easier to fake photos and as juries become more skeptical about what they see.
Although challenges to digital photos come in all types of criminal and civil cases, they are especially pronounced in child-pornography cases because of a 2002 U.S. Supreme Court decision striking down a ban on computer-generated child pornography. Defense attorneys are trying to use the ruling to introduce reasonable doubt in jurors' minds about the images' authenticity.
Prosecutors still generally prevail, but "this has certainly created an additional burden," said Thomas Kerle of the Massachusetts State Police. "I can say that unequivocally, it has made the prosecution of these types of cases more difficult. It takes ... resources I think could be better applied to investigating" more cases.
Drew Oosterbaan, who heads the U.S. Department of Justice's Child Exploitation and Obscenity Section, said prosecutors sometimes submit only photos they can easily verify because outside experts can be expensive — with travel, hotels and consulting fees, along with possible delays.
"This can affect the sentence the defendant gets," he said. "Before (the 2002 ruling) we would generally charge all the images."
Oosterbaan added that although defense lawyers have the right — and duty — to challenge evidence, they are doing so without "any shred of evidence there are wholly computer-generated images being generally circulated and passed off as real children out there."
And many law-enforcement officials worry that the time and money needed to withstand any challenges will only grow as technology improves and makes it more difficult to tell a computer-generated image from a real one.
"I feel that pretty much we can tell the difference right now," said Karl Youngblood of the Alabama Bureau of Investigation. "How much longer that's going to last, I don't know with the technology going at the rate it's going."
Of course, there's a cost to defendants as well — sometimes more so because federal law limits where and when the defense may review images to restrict their distribution, meaning experts must often travel with expensive equipment to a police lab in another city.
"If something becomes more difficult for the government to prove, so be it. They have the burden of proof," said First Amendment lawyer Louis Sirkin, lead counsel in the challenge that led to the 2002 Supreme Court ruling.
Child pornography is illegal in the United States, but the Supreme Court in 2002 struck down on free-speech grounds a 1996 federal ban on material that "appears to be" a child in a sexually explicit situation. That ruling covers computer-generated images, though morphing — such as the grafting of a child's school picture onto a naked body — remains illegal.