EVERETT — Her name was written in the thick murder book.

Three decades later Snohomish County sheriff’s detectives came knocking on her door. She knew why the two men were there. The moment finally had come to share the secret she’d been lugging around since she was 18 years old.

She could tell them who killed Susan Schwarz.

The words eventually tumbled out. She had been in the small Lynnwood-area home in 1979 when Gregory Johnson grabbed a pretty, young woman out of her shower, tied her up and put a bullet in her head.

Johnson, then 26, looked up to find his teenage girlfriend in the room. He shot the victim again.

“It’s that easy. This is what happens to people who (expletive) with my life,” the woman recalled Johnson saying, the gun still gripped in his hand.

The teen had already felt the rage of his fists. The threats he made against her family pounded any courage out of her. She would be to blame if they got hurt, he said. Fear bought her silence.

Then last year, two dogged detectives asked her to tell the truth and give a grieving family answers.

“I had this immense sense of relief,” the woman told The Herald last week.

The Herald is not naming the woman, now 50. She is considered a witness to a violent crime and prosecutors refer to her only by her initials in court papers.

A Snohomish County judge on Friday sentenced Johnson to a minimum of 24 years in prison for the death of Susan Schwarz. The Seattle ex-con, 58, pleaded guilty in January to second-degree murder, finally admitting that he was responsible for the slaying.

Because the murder happened two years before the state Sentencing Reform Act, Johnson’s fate ultimately lies with the state’s Indeterminate Sentencing Review Board. They will decide if he ever walks out of prison again.

Prosecutors believe that Johnson killed Schwarz out of revenge. He blamed her for meddling in his marriage.

Schwarz, 24, was a high school friend of Johnson’s estranged wife. The woman had confided in Schwarz that her husband beat her. Schwarz helped her friend move into a shelter until the woman could leave the state with the couple’s young son. The woman later returned to Washington and spent time with Schwarz in the weeks before the murder.

Back then detectives listed Johnson as a suspect. They took down the names of people in his circle, including his then-girlfriend. Over the years, Johnson was questioned at least twice about the homicide. The first time he told investigators he’d been fishing with his brother in Edmonds the day of the shooting. Police were unable to confirm his alibi. About seven years later, detectives questioned him again while he was in prison for robbery. He implicated his brother in the murder.

At the time, there wasn’t enough evidence to prosecute either man, sheriff’s cold case detective Patrick VanderWeyst said.

VanderWeyst joined the cold case squad in 2010. Teamed up with veteran detective Jim Scharf, the homicide cops are assigned to investigate dozens of unsolved murders and missing persons cases. A majority of the victims are featured on the county’s deck of cold-case playing cards. Schwarz is on the queen of hearts. Her homicide was featured in The Herald’s yearlong series on the unsolved cases.

In recent years, detectives pored over the old case files, noting what work had been done and where there were holes. They shipped off evidence to be tested using today’s more advanced forensic technology.

A tip in March 2010 pushed the Schwarz case up the priority list. An inmate had seen the cold case card featuring the 1979 murder. He told detectives that Johnson had admitted to killing Schwarz. That kick-started the case, VanderWeyst said.

They began to take a hard look at Johnson and how his life intersected with the slain woman’s. Inside the case file, they found the name of Johnson’s then-girlfriend. She’d never been questioned about the case. She might be able to fill in some blanks. Maybe Johnson talked to her about his involvement?

The detectives didn’t know that she would provide critical evidence to put the killer away — the first conviction in the cases featured in the cold case cards.

The woman met Johnson when she was just 17. Her father had died about nine months earlier and her family was reeling from his death. With Johnson’s encouragement, she became alienated from her mom. She moved in with the older man and the relationship quickly became violent, the woman said. He threatened to hurt her if she left. He allowed his friends to abuse her.

The day of the murder, he told the woman they were going to see his friend who owed him some money and drugs.

The woman didn’t know the victim’s name or even the address where the homicide happened.

She believed Johnson when he told her the cops would see her as a suspect. She wasn’t sure what legal responsibility she’d bear, but she was certain that if the detectives came for her, she’d answer their questions. She also was convinced that Johnson would go after her family if she told the truth.

“I can’t say I did it right, but I did the best I could,” the woman said. “I was sorry Sue was dead. I’d have done anything in my power possible at the time to stop it if I could have. She wasn’t coming back though. I knew my mother would be a victim. I had to protect my mom.”

The woman split up with Johnson. She tried to put the past behind her, breaking off ties with high school friends. She stopped going by her childhood nickname. She became a nurse and a mom. She never stopped looking over her shoulder.

Even as time went on, her fear didn’t go away.

Johnson called her mother’s house after he got out of prison for robbery. The woman was visiting her mom and spoke with him. He reminded her that he was still around and knew how to reach her family.

“It drags on you,” she said.

She thought of the slain woman and her family.

“She didn’t deserve that. She was only standing up against abuse,” the woman said. “Her family deserved to have answers long ago.”

Gary Schwarz had learned to live without knowing who took his big sister’s life. He had no choice. He carried some small hope that the killer would be caught. He worried that the person would hurt others.

On Friday, he and his younger sister, Valerie Rau, finally got to face the man who robbed them of their sister.

“The desire to help her friend should not have cost Sue her life,” Gary Schwarz said.

The defendant’s motivation to kill her was as senseless as the man’s existence, he said.

“He took from our family our sense of security, our belief in kindness in others, our belief in right and wrong, but most of all, he took Sue from us forever,” Rau wrote in a letter to the judge.

Gary Schwarz asked the judge to protect the woman who helped the detectives and Snohomish County deputy prosecutor Lisa Paul put Johnson behind bars. He said he feared for the woman’s safety if the convicted killer was released any time soon.

Gary Schwarz met the woman in January after the defendant pleaded guilty. The woman felt she owed the family an explanation and an apology.

“I feel like I didn’t do enough” she said.

The slain woman’s family sees it differently. They hugged her on Friday after Johnson was hauled away in handcuffs.

They are grateful the woman broke her silence. They are thankful for the determination of two detectives who didn’t forget their sister.

They wonder how many other families could get answers if the right person was willing to step forward with the truth.

Diana Hefley: 425-339-3463; hefley@heraldnet.com.