i'm sure they would have taken it. >> the fact that i didn't confiscate it doesn't make it go away. it was there. >> the nylon cord would never be seen again. >> could have been the murder weapon, as far as i knew. >> yet, fbi supervisors decided to let wayne williams go that night. >> we first of all didn't have a body. so -- secondly, there was no one who saw wayne williams outside of his car. there was no one that saw him throw anything overboard. >> two days later, only a mile downstream from that bridge, another body. after two years, one suspect now, wayne williams. when we come back, the lie detector test.