before jamie was killed, he hadn't seen her for two days. on the night of the murder, he said he was at home. >> i was playing computer games like a good nerd. >> did you have anyone there to corroborate your alibi? >> i think my roommates were there, but they were both asleep. i had nobody right there sitting there with me. >> so the boyfriend's alibi wasn't solid. and as they spoke, the detective was looking carefully for signs he might be hiding something. >> he was cooperative. apprehensive. he said everything was fine in their relationship. >> the detective asked chuck for dna, and he said yes. and when they asked him for a polygraph, he agreed to that, too. but here's the thing with that last part, the polygraph. >> failed the test. >> that's a bad sign for you, right? >> it's a bad sign for him, yes. didn't tell you that he's guilty, but he was a very strong person of interest. >> and what's more, the detective had been speaking with jamie's friends who said the relationship wasn't fine.