. >> reporter: dave dooley, the janitor. >> dave dooley was with ed yuska when the body was found. >> reporter: doug tungate, a a warehouse worker. >> doug tungate and joe siegert were the two that saw michelle when she came in. >> reporter: and dan mockbee. >> of course, dan mockbee because he's the husband. >> reporter: a short list of potential suspects for prosecutor linda tally smith. >> i've referred to this case as almost being like the game of clue because you have a very small group and it's a matter of accounting backwards and excluding people. >> reporter: so that's what faced investigators. in which room? with what weapon? and finally, who? >>> coming up -- the questions begin. where was michelle's husband dan the morning of the murder? >> i was sleeping. what a great alibi, right? couch and she sleep on the bed? >> reporter: michelle mockbee's siblings remember her as the big sister who literally couldn't lose. she won every contest there was for like a two-year run. >> yeah. you name it. she won tvs. flat screen tvs. >> tickets to everything, gift cards, you know, everyt

to take. >> reporter: detectives matched the truck to its owner, david dooley, the janitor. >> dave dooley's truck is seen leaving the parking lot at 6:31 that morning. >> reporter: right after the murder? >> that's right. that's right. >> reporter: and detectives could tell from the security tape that dooley had returned to the warehouse around 7:00 a.m., in time to be with ed yuska when he discovered michelle's body. detectives went to the apartment david dooley shared with his wife janet to ask where he went during that half-hour trip. >> they got there at 6:00 -- about 6:30 in the evening. and i kind of figured it would happen just to do a follow-up. >> he told me why he left the building. that he was trying to call his wife. she wouldn't answer the phone. >> my wife does take ambien to help her sleep at night and i went home to check on her, make sure she was okay. >> reporter: his wife, janet, said her husband often worried about her health and would check in on her. >> he drives me crazy with, janet, did you take your medicine? janet, did you take your that's just the kind of person h