MARCUS HOOK, Pa. — A Pennsylvania man has been charged with murder and kidnapping more than 40 years after an 18-year-old woman was killed, prosecutors announced Friday.

Investigators had long suspected two men named in the announcement Friday had played a role in the death of Denise Marie Pierson, who was reported missing in April 1981 after she failed to return home from visiting a friend in Marcus Hook. Her body was found in July 1984 near the railroad tracks in Marcus Hook about 300 yards from the home of one of those suspects.

Wayne Anthony Walker, 58, was charged Thursday with multiple counts of murder, kidnapping and conspiracy. It was unclear from court records if Walker, who was being held at the county jail on unrelated assault charges, had an attorney.

Delaware County District Attorney Jack Stollsteimer and State Police investigators also announced that Peter Horne, who died in 2013 while incarcerated on unrelated stalking charges, was a co-conspirator in the young woman's death. Investigators said two other individuals are still under investigation for their potential role and offered a $5,000 reward for information leading to additional arrests.

"For forty long years the family of Denise Pierson has sought answers in connection with the death of their loved one. We hope that today's announcement brings a measure of healing and closure that they've been denied for too long," Stollsteimer wrote in an emailed statement.

Over the years, investigators had interviewed Walker, Horne and other suspects, including after they say Walker gave details of the killing to a former cellmate when he was incarcerated. And after a call placed to a trauma center claiming responsibility for killing Pierson was traced back to Horne's home. Over the years, physical evidence including batons known as "blackjacks," rope, items of clothing and jewelry were recovered, but investigators felt they did not have enough evidence to charge the men in Pierson's death.

Investigators re-opened the case in 2018, and in reviewing evidence, re-discovered a 6-inch folding knife that had been found with Pierson's remains. They also re-interviewed acquaintances of the suspects and began piecing together that several of the suspects had over the decades revealed details of the killing to those potential witnesses.

In 2021, troopers contacted a forensic expert at the Florida Institute of Forensic Anthropology and Applied Sciences at the University of South Florida who re-examined photos of the remains and other evidence and was able to show Pierson had a puncture wound along her neck near her jaw from a sharp weapon matching the folding knife. Investigators say the knife and the new autopsy information helped corroborate statements from potential witnesses.