The will and determination of an Oregon detective led him to unravel a brutal murder case that’s been unsolved for almost 38 years.

USA Today reports that in 1979, Janie Landers, an 18-year-old Salem teen who functioned at the level of an 8-year-old, was viciously raped and murdered. Janie disappeared on March 9 from the Fairview Training Center, a now-closed state facility for people with developmental disabilities.

Detectives working the case indicated that employees at the center said they noticed an unfamiliar man in a “yellow or gold-colored vehicle,” according to USA Today. Another witness told authorities that a “pot-bellied” man walked up to Janie and started talking to her. Yet, after witness accounts and a composite sketch drawn of the suspect, detectives couldn’t gather enough information to locate him.

More than 38 years after Janie Landers' brutal death, a detective was finally able to tell her family who did it. https://t.co/g3uvuWSh5v pic.twitter.com/GRYqJ8eDEL

— USA TODAY (@USATODAY) November 3, 2017

Five days later, authorities found Janie’s lifeless body dumped on a remote path close to Silver Falls State Park. According to autopsy results, someone slit the teen’s throat, hit her over the head, and sexually assaulted her. Authorities said she likely died the same day she was abducted.

The suspect left behind little evidence, and after clearing several people, detectives were stumped. The case eventually turned cold, but Janie’s sister, Joyce Hooper, who was 13 when the murder occurred, wouldn’t give up.

Throughout the years, Hooper continued to ask detectives to reopen the case. She got a break in  March 2015, when she asked again and explained she wanted her 82-year-old father to see justice before he passed away.

OSP Detective Steve Hinkle took on the case and started from the beginning, carefully going over hundreds of reports while interviewing witnesses and talking to authorities who once worked the case. He noted that investigators said that Janie was strong, feisty, and probably “fought for her life,” meaning the suspect’s DNA was likely on Janie or the clothing she wore.

According to the Oregon Statesman Journal, crime lab forensic scientists re-examined the clothing Janie wore when she was attacked, and confirmed that a blood stain found on her shirt matched the DNA of a male. Detectives then matched the DNA to a convicted felon, Gerald Kenneth Dunlap, who had a violent criminal past involving rape and armed robbery. A judge in Tennessee sentence Dunlap to life in prison in 1961, but he was granted parole 12 years later.

After moving to California where he was required to register as a sex offender, Dunlap made his way to Oregon, where he found a job at Fairview Training Center and got married. He worked at the center as a laundry employee until 1983, and was never once considered a suspect. Records indicate he lost his job after reportedly making unwarranted advances toward a female employee.

In 1996, police arrested Dunlap after he made a sexual advance towards a minor girl, a family member. A jury found him guilty and a judge sentenced him to prison. He ultimately died there in 2002.

Prosecutors theorized that Dunlap likely asked Janie if she needed a ride. When she accepted, he threatened her and assaulted her, but probably didn’t realize her strength, which resulted in him killing her when she fought back and tried to stop the sexual attack.

“Janie’s unexpected level of strength and resistance, however, would have both surprised and frustrated Dunlap who resorted to killing her when his sexual attack was thwarted,” prosecutors said.

On Monday, Hinkle presented Janie’s father, 84-year-old Richard Landers, with Janie’s hair ties and her and a pair of earrings. The family was grateful for the detective’s hard work.

“It’s not much. But it represents the end to this case,” Hinkle told the Statesman Journal. “We’re grateful we could do this for Janie. We’re hopeful her family can find closure to this horrific chapter of their lives.”

[Feature Photo: Handout]