A BRUTAL MURDER - POLICE HAVE DNA EVIDENCE, BUT CAN'T MATCH A KILLER - SO HOW DID A YOUNG FILMMAKER END UP A MURDER SUSPECT?

"48 HOURS" Investigates in "The DNA of a Killer" on Saturday, April 15

Nearly two decades after an Idaho teenager was killed, New Orleans filmmaker Michael Usry, the producer of a short film about a brutal death, found himself the suspect in the teen's murder. What led police to the auteur?

Anne-Marie Green and 48 HOURS investigate the 1996 death of Angie Dodge and the unusual police hunt for her killer that led to Usry in "The DNA of a Killer" to be broadcast Saturday, April 15 (10:00 PM, ET/PT) on the CBS Television Network.

"Nobody every thinks that they're gonna get picked up by the police and taken into an interrogation room and questioned about a murder," Usry tells 48 HOURS. "When it happens to you, it's definitely a game changer."

Angie Dodge was brutally murdered in 1996. The killer left behind a semen sample on her body, which police and her family believed would quickly lead to the person who murdered the teen. Police tested the DNA of men she knew; none matched. Then came along Christopher Tapp, who knew Dodge. His DNA did not match either, but after 28 hours of interrogation over 23 days, Tapp confessed to being there when she was killed. He said that he participated while others stabbed her. One of the men there, he said, was named Mike. But with no last name it seemed like a dead end. Tapp was convicted of killing Dodge. Officially, though, the murder case was still open because Tapp's DNA didn't match the man who left semen at the crime scene.

In 2014, police took a new approach to try to find a match to that DNA. They searched a public database that had been bought by Ancestry.com. The goal was to find a close match, perhaps a family member to the alleged killer, through a process called familial searching. The search resulted in a partial match that sounded like a strong lead. Armed with a warrant, police got Ancestry.com to reveal the name of the anonymous man behind the DNA sample. His name was Michael Usry Sr. and it turns out he had a son: Michael Usry Jr. Police wondered if Usry Jr. could be the "Mike" that Tapp told them about.

Usry Jr. is a filmmaker with a short film titled "Murderabilia." Given the subject of Usry's film, along with the fact he'd been through Idaho Falls at one point in his life, police thought they had their man.

But in truth, Usry Jr. had nothing to do with the 1996 death of Dodge and was officially cleared. Still, his story raises serious questions about what happens when police use publicly available DNA databases to solve cases - and what goes on when an innocent man is tagged as a suspect.

Usry Jr. has now joined with Angie Dodge's mother to search for the man who left his DNA at the scene. And through their search, they came to believe that Chris Tapp, the man who was serving time for the murder after his confession, was in fact innocent. 48 HOURS follows their fight for justice and their hunt for a killer. "Angie was my only daughter, and she's my baby," says her mother, Carol Dodge. "I'll never stop missing her."

48 HOURS: "The DNA of a Killer" is produced by Judy Rybak, Elena DiFiore, Lindsey Schwartz and Chris O'Connell. Gregory McLaughlin is the producer-editor. George Baluzy, Michael McHugh and David Spungen are the editors. Patti Aronofsky is the senior producer. Susan Zirinsky is the senior executive producer.

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