A Washington State man has been arrested in the 1986 killing of a little girl found raped and murdered after being abducted from a park, authorities said.

Gary Hartman, 66, was charged on Friday with first-degree murder and first-degree rape of Michella Welch, who was just 12 years old when she was taken from a park in Tacoma on March 26, 1986.

She had taken her sisters to Puget Park to play and went home hours later to make sandwiches.

"When she returned, she may have gone looking for her sisters who had gone to a nearby business to use a restroom," Tacoma Police said in a statement.

Her sisters found her bike and the sandwiches on a picnic table hours later.

Michella’s body was found later that day. She had been sexually assaulted and died from a cut to the neck and blunt force trauma to the head, reports at the time said.

Police worked the case for more than three decades and in May, they tapped a genetic genealogist to help.

DNA believed to have belonged to the suspect was used to build a family tree on public genealogy websites. They ran it through a public database and received “a significant match,” officials said.

The hit led to Hartman and his younger brother, and detectives began their surveillance of the pair in early June.

An investigator following Hartman watched as he ate lunch and disposed of a used napkin, which the officer was able to get from a server, the News Tribune reported.

On Tuesday, the DNA came back as a match as the DNA found on Michella’s body.

Hartman has no prior criminal record.

Records show Hartman lived less than two miles from Puget Park the year Michella was killed.

In 1998, he obtained an active license as a registered nurse, and at the time of his arrest, he worked at Western State Hospital.

Hartman was being held on $5 million bail. He is expected to be arraigned on Monday.

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