it was nerve-racking. >> but dan mockbee passed the polygraph. time, the husband didn't do it. and with dan, cleared the detective focused on who was there that morning. 13 employers were working in the regular shipped when michelle was killed. detectives interviewed all 13. >> with each person i talked to, there is no blood, there is no evidence they've been involved in anything. >> if it's one of these people you are interviewing, they've disguised it well. >> they have. >> there was nothing suspicious about any of the 13 interviews. so, detectives started methodically digging through other evidence. starting with thermal fissures security camera footage, and right away, they spotted something unusual that happened in the morning of the murder. a vehicle in the parking lot not entering but leaving, around the back of the building. detectives matched the truck to its owner, david dooley, the janitor. and one of the workers who found michelle's body. >> dave dooley's truck is seen leaving the parking lot at 6:31 that morning. >> right after the m