Investigators long thought a 5-year-old South Carolina boy found strangled in 1989 was killed by his father and stepmother. But it took 34 years of scientific advancement to link microscopic fibers found on the boy’s shirt to a ligature that investigators located at the couple’s home, a sheriff said.

Victor Lee Turner, 69, and Megan R. Turner, 63, have been charged with murder in the death of 5-year-old Justin Turner, Berkeley County Sheriff Duane Lewis said at a news conference Wednesday.

The boy’s body was found inside a cabinet in a camper behind the Turner home in March 1989.

Investigators immediately thought the killing scene had been staged and caught the couple in lies, including that he had gotten on the school bus the morning he disappeared, Lewis said. Megan Turner was charged with murder shortly after the boy’s death, but prosecutors dropped the charge, with the condition that they could refile it if more evidence emerged.

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Scientific advancements, combined with evidence collected in 1989, was the push needed, the sheriff said.

Tiny fibers from a ligature that investigators found at the home shortly after the boy’s disappearance were found to match those found on the boy’s shirt, sheriff’s deputies said in the arrest warrants.

“That enabled us to tie in the murder weapon that we believe was used to strangle Justin to clothing and fabric on his clothing at the time of his death,” Lewis said.

Investigators suspected the Turners from the beginning, based not only on the ligature, but the couple’s behavior. Other possible evidence was that food from a dinner the family had eaten the night before Justin was reported missing was found during an autopsy to be only partially digested. Investigators said that indicated the boy was killed not long after he ate. The couple said the last time they saw Justin alive was the next morning as they got him ready for school.

The child’s body was found two days after he was reported missing. Just as a massive search was getting underway, Victor Turner entered the camper as a TV camera filmed him and seconds later said he found the body among the many cabinets and drawers in the camper, deputies said.

Turner didn’t check to see if the boy was alive, instead backing out and saying someone had hurt him, according to the statement.

“He looked dead. I could feel something was wrong with him. I did not touch him,” Turner later told investigators.

Before the body was discovered, a witness said Turner asked a law enforcement official what might happen to a family member who had harmed the boy, deputies said.

Deputies said the couple do not have lawyers. They are being held without bail at the Berkeley County jail after being arrested at their home in Laurens County, about a three-hour drive away.

The sheriff said deputies gave them ample time to talk during the ride after reading them their rights, but they chose not to.

“I never got one phone call — one phone call — from his daddy or his stepmother. ‘What are y’all doing about my son’s death?’ Not one. What does that tell you?” Lewis said.

Several members of the boy’s family were at the news conference, including Amy Parsons, who was 8 when her cousin died. She said while many of her relatives grieved and cried and demanded justice — including the boy’s mother, who has since died — the Turners moved away and disconnected.

“Put these two people where they deserve to be because they walked for 34 years,” Parsons said. “They had freedom for 34 years while our family suffered.”