The male nurse suspected of killing a 12-year-old girl more than three decades ago has been officially been charged with first-degree murder after DNA from a napkin led to his arrest.

Gary Charles Hartman, 66, of Tacoma, Washington, was arrested at 3.19pm on Wednesday in connection with the death of Michella Welch.

Tacoma Police Chief Donald Ramsdell said during a press conference on Thursday that unknown DNA was found at the crime scene at the time and numerous men were investigated based on witness statements, but Hartman was not one of them.

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Gary Hartman (pictured), 66, of Washington, who is suspected of killing Michella Welch, 12, in 1986, has officially been charged with first-degree murder after DNA from a napkin led to his arrest

Hartman was arrested at 3.19pm on Wednesday in connection with the death of Michella (pictured)

According to KOMO News, in 2006, a male DNA profile was put together using the unknown DNA found at the scene of the crime.

After a search of the state and national data bases, detectives came up with no leads.

This year, authorities began working with a genetic genealogist at Parabon Nanolabs.

The firm was able to find a match with two brothers who lived in Tacoma in 1986, Hartman was one of those brothers.

During the press conference, one of the detectives said they were then able to get a napkin Hartman had used after they followed him into a restaurant.

It was in the restaurant that one of the officers observed him 'using the napkin multiple times' before throwing it away.

The officer then took the crumpled napkin from the trash and used it to confirm Hartman's DNA.

Police said, to their knowledge, Hartman did not know Michella or her family, but he did live in the area where her body was found.

Tacoma police said they spent much of Wednesday searching Hartman's home in Lakewood after his arrest.

Investigators said they were processing the house in connection with the case.

According to Tacoma police, at 10am on March 26, 1986, Michella and her two younger sisters were visiting Puget Park.

Michella briefly left the park to get lunch for her sisters. When she returned, she may have gone looking for the younger girls who had gone to a nearby business to use a restroom.

When Michella’s sisters returned to the park around 1pm, they found the 12-year-old's bike and the lunch bag she had packed for them on a park table, but she was nowhere to be found.

Police launched a search for Michella shortly after 3pm, and her body was discovered in a gulch later that night, according to the Tacoma Police Department.

Michella had been sexually assaulted and had her neck slashed.

Michella was playing with her two sisters in Puget Park in Tacoma (pictured in 1986) when she vanished, only to be found slashed to death in a gulch hours later

Five months later, 13-year-old Jennifer Bastian was abducted from Tacoma's Point Defiance Park and was found strangled to death in the woods weeks later. She, too, had been sexually assaulted.

For years, Jennifer's murder was believed to be linked to Michella's death, but in 2016, a new DNA test determined that two different killers were responsible for the girls' murders.

In May of this year, 60-year-old Robert Washburn was arrested in Illinois on suspicion of killing Bastian more than 30 years ago. He has pleaded not guilty to first-degree murder.

Neighbors in Tacoma described Hartman, the suspect in Michella's slaying, as a pleasant man who collected vintage cars and lived with his wife.

Hartman was working as a registered nurse at Western State Hospital up until his arrest on Wednesday.

In addition to a murder charge, Hartman is also facing a first-degree rape charge.

He is considered a flight risk because he has significant assets and bail was set at $5million.

Hartman is currently being held at the Pierce County jail awaiting arraignment.