As seen on TV: ‘CSI’ versus forensic science

“CSI: Crime Scene Investigation” and other TV dramas have created unrealistic expectations that can swing jurors, law enforcement officials say. Defendants may walk free in cases that should be slam-dunk convictions.

This phenomenon, called the “CSI effect” in law enforcement, has left many investigators feeling frustrated.

Doug Seccombe, special agent for the FBI in Chicago, said many jurors don’t understand that television shows often don’t mimic reality.

“They think we’re going to get fingerprints at every crime scene,” said Seccombe, who leads the FBI’s evidence response team in Chicago. “It’s not like that in reality. Sometimes we don’t get anything.”

There have been times when prosecutors have gone to trial with a confession and still lost the case, said Seccombe at a lecture hosted recently by the Chicago Council on Science and Technology.

During deliberations, which are done behind closed doors, “one of the jurors says, ‘Hey, I saw this show on TV. They didn’t get a fingerprint, and they should’ve gotten a fingerprint.’ Now they just convinced 11 other jurors to let this person go,” Seccombe said.

Prosecutors often talk to jurors after a verdict has been reached to find out why they voted the way they did.

Matt J. DeSarno, a supervisor in the FBI’s Chicago field office, recalled a case where a defendant was acquitted based on a defense his lawyers didn’t even present at trial.

DeSarno said jurors listened to a recording of a drug deal. Prosecutors argued that the voice on the recording was the defendant’s.

But once jurors began deliberating, one of them said, “Wait a second. The FBI didn’t use voice-identification software,” according to DeSarno.

That’s because the FBI doesn’t have voice-identification software, DeSarno said. Still, jurors weren’t convinced the voice on the recording was the defendant’s.

“So we had a jury conjuring up some software tool that didn’t exist,” DeSarno said.

Jurors aren’t the only ones who watch crime dramas. Many criminals think they have learned to cover their tracks by tuning in to TV crime shows.

Seccombe worked a case where killers cut up the body of their victim with a chain saw inside a garage.

They wore gloves, masks and specialized tie-back suits while dismembering the corpse, knowing from watching TV that they couldn’t afford to leave behind a stray fingerprint or strand of hair.

But they did leave behind cigarette butts laced with their saliva, which were tested for DNA and ultimately used to link them to the murder.

Even though shows like “CSI” have made his job harder, Seccombe knows they won’t be taken off the air anytime soon. As long as ratings remain high, networks will continue to churn out these programs.

Still, he says, it’s frustrating when cases — which investigators work so hard to put together — are unraveled by a TV show.

“They see a lot of this stuff on TV in the last 10 years, all these ‘CSI’ shows, and they think we can pull a rabbit out of our hat,” Seccombe said. “And it’s not like that.”