>> there is a common misconception that momentous events occur in great cities, that justice is handed down true and pure from marble palaces. but what would lady justice say about the story you're going to see now, about a nobody in a nowhere town, a story that is, well, what would they say?

>> this is crazy. how can you do this.

>> i couldn't believe it.

>> this is definitely a shock.

>> yes. it is all of those things, shocking, unbelievable, crazy. and tied with an unbreakable chain to a summer's night in a poor forgotten back water more than 30 years ago. the town is poplar, montana , june 15th , 1979 . summer was here. school was out. kim nees, 17, school valedictorian , national honor society graduate, was finally about to escape this town for college. around about midnight kim left her house to join the end of school party. it was the next morning when police found the family pickup at a well known party spot a half mile outside town. they followed a trail of blood from the truck down a rotted dirt track, 250 feet or so, to the poplar river , and there they found the battered body of kim nees.

>> the term i used was overkill.

>> dean mallom was undersheriff, later the sheriff in the investigation.

>> there were 20 to 21 blows to kim 's skull, which any of which could have caused her death.

>> there was rage involved?

>> there was a high level of rage, someone was very angry.

>> at the crime scene , no shortage of evidence. blood everywhere, inside the cab of the pickup, fingerprints, more than two dozen, multiple footprints in and around the trail where kim 's body was dragged to the river. and on the truck near the passenger door, a palm print in blood. the fbi lifted the print, said it would have to have been left by the killer.

>> we worked very, very, very hard at determining whose that was.

>> why kim nees? wasn't a robbery or sexual assault. people do talk. and around town the story was that this was call it a jealousy killing. kim was popular, attractive, class valedictorian. the boys loved her. and she was about to leave poplar behind for good. the story was that this was local kids, mostly girls, who beat her to death. so went the rumor.

>> that was one of the, again if you will, the theories that folks around town had is that there may have been three or four of kim 's peers that were involved with her death.

>> bobby clincher heard the talk, she lived down the block from the knees family.

>> what did you hear?

>> her grandfather had told me all indications are that it was girls.

>> though many of poplar's teens, boys and girls wound up on a list of potential suspects, including bobby's son barry who once dated kim 's sister.

>> did you question him harshly about it?

>> uh-huh, he said repeatedly he didn't know anything about it. the only thing he knew is what he had heard, what he had been told.

>> that's what all the kids told the police, too, and nothing happened. nobody was arrested. three years went by. then in january, 1983 sheriff mallon picked up the phone, found himself talking to a detective from way down south.

>> he asked if i was aware of an individual by the name of barry beach , wanted to know if mr. beach was or had ever been a suspect in homicide in roosevelt county .

>> barry was almost 21 by then. he had gone to louisiana to be with his father and stepmother. wasn't going well. in fact, his stepmother had him arrested for helping his step sister skip school. then told arriving police officers that barry was once questioned about the murder of kim nees in montana . well, it just so happened investigators in louisiana were scratching their heads over murders of three women in their county. so could beach be their killer?

>> from talking to sheriff, the fact he was a viable suspect.

>> so the detective that called the montana sheriff interrogated beach about the louisiana murders. what made you think he was the kind of guy would be your prime suspect ?

>> the fact that he was a suspect in a murder already.

>> so the detective put barry in a little room here at the sheriff's office and groomed him. f -- grilled him for two days. after many hours of questioning, his answers about kim nees changed, according to jay vy anyway.

>> we asked him were you responsible. this part of the interview, he kept saying i don't remember if i was or not.

>> soon the detective was joined in his work by commander alfred calhoun, known as something of a closer. vy stepped out of the room while the commander worked on barry .

>> alfred stepped out of the interview, said he wants to talk to you. when i walked in the room, barry was crying, and he admitted to killing kimberly nees.

>> the mystery was solved. all the rumors about other suspects, including that group of girls, long whispered of in connection with the crime, were apparently wrong. vy allowed barry to call his mother back in montana .

>> i said barry , why did you confess to something you didn't do? and he said well, they're going to come back to montana and help me prove i didn't do this.

>> but in montana , helping barry beach was not on the menu. first degree murder was. barry pleaded not guilty, but when his trial began at the courthouse in glasgow, montana , the prosecutor came on very strong.

>> i had a detailed confession that only the killer could have given.

>> within a decade, mark roscoe would be elected montana 's governor. in 1984 , though, he prosecuted barry beach .

>> he gave a very detailed confession that matched the things that were discovered at the crime scene .

>> like what? well, beach described the shirt kim wore, the tire iron and crescent wrench used to kill her, how she was dragged out the driver's side of the pickup, on and on. when testimony was finished, the jury was back in just six hours. the verdict, guilty. and so in the spring of 1984 , the story of the life of barry beach was apparently over. dead man walking , sentenced to 100 years, no parole. but of course, who are we fooling. the amazing story had really just begun.