officer snead, i was not there.l take a polygraph test right now to prove to you that i was not there. >> when you've got somebody in the interrogation room who offers to take a polygraph, that's a strong sign of innocence that should not be disregarded. >> we know you were in the house, okay? >> reporter: but then snead's partner terry walls ups the ante. >> i was nowhere near the house. >> reporter: they have evidence, he says. >> we know you were in the house. we've got evidence that's going to prove you were in the house. >> reporter: they don't, by the way, have any evidence of that. though it is legal for police to lie in an interrogation. >> i want to see this evidence. >> there was a lot of people. you will. >> reporter: just after 3:00 a.m., robert asks for his medicine. he has strep throat, remember. he's also asthmatic. >> i need to take my third dose. i have not taken it. >> i will give you the penicillins once we get going, okay? you -- you work with me and i'll work with you. >> reporter: robert's been