In the segment, Engelberg and his fellow guests examined the scientific evidence of the case and questioned whether it was conclusive enough to hold up in court.
"What our investigation found was that as the case was built, they became less and less interested in doing things that might undermine the case," Engelberg said. "...My guess, and here it's just a guess, is that they didn't want to ask a question they didn't have the answer to. They were afraid it would show something unexpected. And I'd think for scientists, that's exactly what you'd want to do -- is find something unexpected."
The case has since been closed with Army microbiologist Bruce Ivins -- who committed suicide in 2008 -- pinned as the man behind the plot. The FBI still insists it nabbed the right man.