Casey Anthony CSI: A Triumph of High-Tech Forensics?

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Joe Burbank / Orlando Sentinel / MCT / Landov

Crime-scene investigator Jennifer Welch holds up duct tape entered as evidence during Day 16 of Casey Anthony's trial at the Orange County Courthouse in Orlando, Fla., on June 11, 2011

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6. Cyber-evidence is key
To prove their assertion that Anthony searched the Internet for homemade chloroform recipes, prosecutors called on digital forensics experts who recovered searches from Anthony's laptop, even after they had been erased. This may seem like science fiction, but it's a common practice for investigators.

"We start out by forensically preserving that evidence at a point in time," says Cheri Carr, director of the Dallas digital forensics lab for Stroz Friedberg, a digital security firm. The analysts use computer programs to recover data that has been deleted but is stored in unallocated space on the hard drive. It's tedious, complicated work, but the results are compelling for a jury.

"Computer evidence, in my opinion, is one of the best forms of evidence because it's somewhat indisputable," says Erin Nealy Cox, a former federal prosecutor and head of Stroz Friedberg's Dallas office. "Where you might have problems with eyewitnesses contradicting themselves or not remembering, you don't have those types of problems with computer evidence."

While the jurors have seen compelling evidence that someone searched for chloroform, the prosecution has one glaring limitation. "The one piece that [investigators] can't do is put the person at the computer, but there's a lot of circumstantial evidence you can use," Nealy Cox explains. Prosecutors will emphasize that the damning Internet searches occurred on Anthony's computer, while defense lawyers will stress that many people other than Anthony had access to the computer.

7. A guilty verdict might not be final
The prosecution has run some risks in building so much of their case on expert testimony that the forensics evidence is "consistent with" their theory of how the crime was committed. No matter how careful investigators and experts have been, the decision of Judge Belvin Perry Jr. to admit analysis using some of the newer and less-tested scientific methods may give Anthony's lawyers grounds for appeal if she's convicted. This is because Florida, like New York, Illinois and Pennsylvania, is what is known as a Frye state, where courts must follow strict guidelines for what type of scientific evidence is admissible. In a Frye state, the City University of New York's Schwartz says, the judge does not "let testimony in where the danger of unfair prejudice vastly outweighs its probative value." The danger of unfair prejudice, explains Schwartz, is that a jury brought up on CSI will assume that "consistent with" testimony equals definitive identification.

"A jury is not the place for judging science when it's in a debatable, experimental state," Schwartz says, citing Vass's odor-analysis technique. "Until the scientific community reaches a consensus, it shouldn't go to juries."

For Kobilinsky, who was an early proponent for the use of DNA in the courtroom, his objections underscore the weight jurors give to scientific evidence. "There is no question in my mind that when juries hear about science in the courtroom, the science has an impact," he says. "And that is another reason it is essential that we show the jury only reliable science. We can't take a chance, especially in a capital case, of giving them science where the reliability is questioned."

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