Marcia Clark on the Biggest Piece of Evidence Overlooked During the Casey Anthony Trial

On the premiere episode of "Marcia Clark Investigates the First 48," Marcia Clark dives into the high-profile case of Casey Anthony: a Florida mother who was charged with murdering her 2-year-old daughter, Caylee. She was tried in 2011 and found not guilty.

Clark spoke with us about a shocking computer search from the Anthony home, revealed on the show.

What did you think about the Casey Anthony case as it was happening? Did you think Casey was guilty?

Yeah, I did, but not immediately. The defense theory that she was in a dissociative state always struck me as pretty thin. In fact, that's something that I really want to delve into in [my] podcast about Casey Anthony, because we didn't get a chance to go very far into that subject during the show. That is an interesting angle—her mental state: Does her defense claim of being in a dissociative state hold any water?

Of course, we also discovered so much more—the new find about the computer search that was conducted for 'foolproof suffocation.' And between computer records and cell phone records, we were able to determine that the only one at home using that computer at the time was Casey Anthony.

In your mind, is that the biggest piece of evidence that was overlooked during the case?

Yeah. After Casey was first contacted by the police, they took her to every address where she said 'Zanny the nanny' might be with the baby. Then [the police] took her home. And at that point, after they took her home and left her there, that's when the browser history was erased. That browser history included the search for 'foolproof suffocation.'

Just by simple logic, the [most likely] person who would think to erase the browser history is the one who conducted that search, which has to be Casey Anthony.

And there's no way that she could ever be charged or tried again for that case, right?

No, she can't, not in state court. She could be prosecuted for it in federal court because there is no double jeopardy between state and federal. But the feds never take these cases over.