EVERETT — He was their prime suspect in 1977 when his wife’s body was found in the backseat of her yellow Chevy Nova just a few miles from their Mill Creek home.

Marsha Sitton, 24, the mother of a young daughter, had been sexually assaulted and strangled with a clothesline. Investigators worked the case for years but didn’t have enough evidence to prove that the slain woman’s husband, Kerry Sitton, was behind the brutal attack.

That’s all changed, Snohomish County sheriff’s cold case detectives announced Wednesday.

Advanced forensic testing has linked Kerry Sitton to the homicide, sheriff’s detective Jim Scharf said. Forensic evidence together with other circumstantial evidence proves that he is responsible, the longtime homicide detective said.

Snohomish County Prosecuting Attorney Mark Roe recently reviewed the case and agreed. Roe said that he believes there is sufficient evidence to prove to a jury that Sitton killed his wife.

But Sitton will never face a jury. He died Dec. 30, 2004. Sitton, a retired mechanic, had been diagnosed with a brain tumor several years earlier.

The tumor was in remission for about three years but symptoms returned shortly after detectives visited Sitton and his third wife at their Kelso home. He died six months after that interview. He was 52.

“Some people may ask why does this matter since we can’t prosecute the case and send him to prison,” Roe said. “It matters a lot to the people who loved (Marsha Sitton).”

Carla Wilson said detectives never let on that Kerry Sitton was the prime suspect in her sister’s death. Over the years, however, the family began to suspect, Wilson said.

She had known Sitton since they were teenagers. They were in the same class at Edmonds High School.

“I knew he had a temper. I’d seen him mad, but I’d never seen the violent side of him,” Wilson said.

Woman was afraid

Marsha and Kerry Sitton married on July 3, 1970. Their daughter was born two years later, but the marriage fell apart. The couple divorced in 1974.

But Kerry Sitton wanted to spend more time with his daughter and Marsha Sitton told people she wanted help raising the girl. The couple remarried July 3, 1976.

Witnesses later said Marsha Sitton again wanted out of the marriage. She was seeing someone else. “She said she was afraid of how he would react. She said she was worried he might get violent and kill her,” Scharf said. “It’s possible she told him and that’s what happened.”

Two teenagers found the slain woman in her car on June 24, 1977. It was parked on a gravel road near Mill Creek. Investigators believed the young mother had been killed somewhere else and placed in the car.

Detectives found a 12-inch piece of clothesline on the backseat. They believed the killer had cut the rope off the slain woman but forgot to grab the piece behind her neck.

The two teens told investigators that about an hour before finding the car they met a man on the road about halfway between the Nova and the Sittons’ house. The man matched Sitton’s description. The teens bummed some Raleigh cigarettes. The stranger was in a hurry and said he was headed toward 142th or 148th Street SE. The Sittons lived on 146th Street SE.

Detectives called Kerry Sitton at work that morning. He told them that he hadn’t seen his wife since the night before. He said that she had received a call from a friend asking for help. She wasn’t home when he went to work.

Detectives noted that Kerry Sitton’s alarm clock was on the coffee table, not on the nightstand in the bedroom. The linens for the bed were in the dryer. There were no garbage cans anywhere inside or outside the house. Sitton had Raleigh cigarettes.

He reported nothing but “normal” problems in his marriage. He also disclosed he hadn’t had sex with his wife for quite some time.

Five days later he told investigators he and his wife were intimate the night before her body was found. Detectives grew more suspicious. Sitton was changing his story.

Prosecutors declined to file charges, said former Snohomish County Sheriff Rick Bart, who worked the case after the initial investigation.

Case reopened in ‘03

Former homicide detective Joe Ward revived the case in 2003 and sent forensic evidence for testing. Scientists at the Washington State Patrol Crime Lab told detectives they wanted a genetic sample from the suspect to compare against crime scene evidence taken from the slain woman.

Scharf and detective Pat Vanderwyst traveled to Kelso in 2004 to talk with Sitton. They found him sitting in his garage. He agreed to talk with them if his wife was there. Sitton had remarried shortly after his first wife’s death. That marriage ended and Sitton remarried again in the early 1980s. He and his third wife raised four daughters, including the girl he had with Marsha Sitton. He didn’t have any run-ins with law enforcement.

Detectives learned that Sitton’s brain tumor had affected his memory. He could recall some details, such as Bart confronting him about his first wife’s death. He agreed to let detectives swab the inside of his mouth to collect DNA. He also agreed to take a polygraph.

After the interview, Sitton begun to suffer seizures. He died before taking the polygraph, Scharf said.

Investigators learned in 2004 that Sitton’s DNA was on his wife’s body. That wasn’t enough to prove the case. After all, he’d told detectives about being intimate with his wife before her death.

Detectives in 2004 also talked about testing the rope for minute amounts of DNA. The state crime lab wasn’t able to do that kind of specialized testing at the time.

Sitton was dead and there was no chance to prosecute him, but detectives and crime lab scientists recently pursued the case again.

Advanced technology at the state lab made it possible to extract a genetic sample from the clothesline. The tests showed that material found on one end matched Kerry Sitton’s DNA, Scharf said.

“The family needs to know,” he said. “Our job is to seek the truth. There are people out there that need to know what happened.”

There are many more families that need answers.

“Please don’t give up hope. There’s always a chance,” Scharf said. “We’re not going to give up on any of these cases.”

The sheriff’s office in 2008 created the state’s first deck of cold-case playing cards featuring unsolved homicides and missing persons cases. Marsha Sitton’s murder wasn’t featured in the deck because detectives were confident they were close to solving the case.

A federal grant last year provided a boost to the sheriff’s office cold case squad. They added two more detectives and a consultant. Detectives are reviewing evidence in dozens of unsolved cases and more testing is under way.

“This closes a chapter for my family. It definitely gives us closure to have it solved,” Wilson, the slain woman’s sister said. “I just think the sheriff’s office and the crime lab has done a wonderful job. There’s hope.”

Help solve a cold case

See all the cards in the cold-case deck created by the sheriff’s office, and read more about the cases at www.heraldnet.com/coldcasecards.