dennis murphy: detectives finally had a major break in the investigation.om the tyrrell home had turned welcome back to dateline. now, with the conclusion of the collector, here is dennis murphy. >> detectives finally had a major break in the investigation. silver coins, worth around the same amount as the one taken from the terrell home had turned up in a local coin shop. surveillance cameras called the transactional on video. the man certainly looked familiar, but, if there was any doubt, he left a copy of his i. d.. mark porter. >> yes. >> mark edward porter. this is a real license, this was the actual day. >> that's when! >> but selling a lot of coins did not prove that marc porter was guilty of murder. remember, mark also had an interest in the queen business. >> the best explanation for that was just simply that these four coins that marc porter had, it was just a coincidence that they happen to be sold the day after the terral was killed. >> still, the police, ibm executive retired school superintendent, and by all appearances, a pillar of the commun

dennis murphy: tonya priest had gone to the authorities with an explosive allegation.d a man nicknamed thumper had confessed to her that he and two buddies had abducted and murdered heidi allen back in 1994. >>> tonya priest had gone to the authorities with an explosive allegation. she said a man nicknamed thumper had confessed to her that he and two buddies had abducted and murdered heidi allen back in 1994. and she was devastated when the prosecutor checked out her story and ultimately chose not to believe her. >> i was doing it because i was a good person. and that is how i felt. >> but tonya would not give it up. she was convinced that an innocent man, gary thibodeau, was in prison. she made calls and was eventually put in touch with a new york federal public defender named lisa peebles, somebody who had ties to the defense lawyers who had worked on thibodeau's failed appeals. >> tonya felt as though things were on this by the time she called our office. >> lisa, the lawyer, listened to that secretly recorded phone call between tonya and her childhood pal and came

dennis murphy: a sunday morning just before 7:30 >> all right! nights only halfway through, taxis, patrons, paula sladewski objected and leaving after the watchful eye of the league security man. >> she got to the sidewalk and then i noticed her and the suspect, i guess they're looking for, walking across the street hand-in-hand. >> you saw them over there because there's a big parking lot. >> yes there's a big parking lot. >> paula and somebody heading towards the lot behind the strip club across the street and guess what? two weeks after the murder bouncers at club's pace war certain they saw the same man again right outside the front door. this guy thought your door people saw that night the one approaching her, they believe they saw that same individual again a few weeks later. >> i believe two weeks later on saturday they saw an individual fitting that description walking in front of the club. >> luis owned club space. he said they call the miami cops who came and questioned him. >> they apprehended him talk to him, and from my understanding

dennis murphy: do you think, i'm in trouble here? these guys are looking for me for this thing?ions for danny. >> you think i'm in trouble? you guys looking at me this? >> no. no. i just figured they are a check mark on their list. people to go talk to. >> once again, dave told the detective he was home for his meeting at 8:30. remember, the night of the murders, he said he was in the bathroom when jordan was dropped off. now, his story was a little different. >> and what they're messing with the dog, i was out back. >> small inconsistencies. but detectives also wanted to ask about the strongest piece of evidence, bullets and shell casings consistent with a nine millimeter. did dave on that type of gun? >> you have a rocker? >> the robe, or no, i saw that during the divorce. yeah, i need the quick cash. >> who did you sell it to? >> i don't know. >> a coworker? some down the street? >> no. off the street. put it out in the paper. >> we ended up looking for that ad and we were never able to find any ad for a nine millimeter by gabe watson. >> but when they looked in dates gun saf

dennis murphy (voiceover): the missing sister, missing daughter was a hole in their universe that thee missing sister, missing daughter, was a whole in their universe that the tierney family simply couldn't repair. >> we felt a little broken. there's a little sadness. you feel a little guild and joy because that person isn't there to experience it with you. it really changed us. my parents were just constantly trying to resolve this, trying to find her. >> for years, susan sister says the parents drove the prairies, surging freddy santa lost, are often what their youngest girls in tow. >> that's their childhood memory? looking for their missing sister. >> looking after their missing sister and looking after themselves because my parents were overwhelmed with the situation. >> it 2002, several years after his disappearance, teen's family had her declared legally dead. >> it didn't give us the closure we needed to have, i feel like. without actually knowing what happened to her. >> what happened to her? where she? >> yeah, exactly. >> two questions you couldn't get answers to? >> yeah.