BANGOR, Maine - A Maine man charged with killing a teenager nearly 36 years ago changed his story so many times over the years that it complicated the investigation and made it difficult to finally bring charges, state police said Friday.

State police arrested Philip Scott Fournier, 55, of East Millinocket, and charged him with murder in connection with the 1980 killing of 16-year-old Joyce McLain. The teenager disappeared while jogging in August 1980, and her body was found two days later behind a school in her hometown. She was wearing only her shoes and socks. Police said she was bludgeoned to death.

CBS affiliate WABI in Bangor reports in the affidavit for his arrest it states that Fournier told his mother Anita Powers he killed her.

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She told police he said: "I am sorry momma. I did it. I killed Joyce McLain" Powers said that he then began to cry and said, "I didn't mean to."

Fournier is on the state sex offender registry, and he was previously identified as a person of interest in the homicide when Judge John Woodcock sentenced him in 2009 to 6 1/2 years in prison for possession of child pornography. He was released from prison just over a year ago.

Philip Scott Fournier in a booking photo released by Penobscot County Jail in Bangor, Maine on March 5, 2016. REUTERS/Penobscot County Jail/Handout via Reuters

Police said Friday that the investigation is still not over, but they believe they have determined Fournier is responsible for the death, and he is the only person who has been charged. Authorities hope the arrest can help McLain's mother, Pamela McLain, get justice for her daughter.

"We are pleased we have been able to bring closure for Pam McLain. She has lived a nightmare," said police spokesman Steve McCausland. "The entire region has been dealing with this death for 3 1/2 decades."

Homicide detectives had interviewed Fournier 22 times since 1980, according to the complaint filed by Detective Thomas Pickering. In the complaint, Pickering said Fournier kept changing his story, at times saying he witnessed others abduct McLain or that he was forced to participate in the abduction.

The complaint said that Fournier over the years had told several people that he was involved in McLain's death, including a pastor who in 1989 told police that Fournier had confessed to him.

The complaint gives no indication of what new information police have obtained that caused them to charge Fournier with the killing. Police declined to elaborate.

Fournier is being held at the Penobscot County Jail. Police said it was not immediately known if he had a lawyer. He'll appear in court to respond to the charge for the first time on Monday in Bangor.

The case helped provide impetus for the state's creation of a cold case unit. The Legislature voted last year to fund it.