Investigators have unmasked the suspected killer behind the 1986 cold case slaying of a Florida nurse using DNA.

Donald Douglas was identified as the murderer of Teresa Lee Scalf, whose throat was slashed in her home almost 37 years ago, the Polk County Sheriff’s Office announced on Oct. 16. Douglas, who was a neighbor of Scalf, died of natural causes in 2008 at the age of 54. 

“We believe it was a sexual rejection,” Judd said. “We saw a lot of defensive wounds. She never had a relationship with him. So we believe that he was angry and upset because she wouldn’t have a relationship with him.”

At the time, Scalf was a 29-year-old nurse at Lakeland Regional Health Medical Center. 

Douglas, who was then 33, was interviewed by authorities in the aftermath of Scalf’s killing, but there had been no concrete evidence tying him to the murder. Investigators said Douglas had no past criminal record and was also cremated after his death, which made connecting him to the killing all the more difficult. 

Some blood, which didn’t belong to Scalf, and which investigators speculated was left by her killer, was found at the crime scene. It was ultimately entered into a local, state, and national database that contained forensic profiles of known convicted criminals, as well as unsolved crime scene evidence, and other missing persons cases. 

For decades, however, it wasn’t matched to anyone, and Scalf’s case went cold.

“When we were able to work the genealogy up into the modern era, [a detective] met with Donald Douglas’ son and said, ‘We’d like a blood sample; we’re working a murder investigation,’” Judd added per WESH. “The son, to Donald Douglas, was totally cooperative and was in horrible shock. His dad, and here’s the key to it, had never ever ever been arrested. Ever.”

Prosecutors for the State Attorney’s Office 10th Judicial Circuit have concluded the case status should be updated to solved due to Douglas’ death. 

Scalf’s family welcomed the news that a killer had been identified in the case.

“Teresa was a wonderful person, the most loving person,” Scalf’s sister, Pam Shade said at a press conference. “She didn’t deserve this. My family didn’t deserve this.”

Her other sister, Lynn Scalf, said Teresa shared that she had some uncomfortable experiences with a neighbor, but didn’t fully describe him, offering that up as a cautionary tale for present-day stalking victims.

“Teresa had told us about some creepy neighbor that had showed up at her house with what looked like he had yanked a flower up out of the ground and slapped it into a pot,” Lynn said during the news conference, according to the Miami Herald. “He was sort of stalkerish, and she had told us about him, but she never described him. So anybody, but especially ladies, if someone’s being creepy, don’t just tell your sisters, tell them what he looks like.”

According to her family, Scalf was murdered roughly a month after becoming a registered nurse. 

“I’ve been a nurse [for] 38 years now,” Shade added. “My brother is a trauma nurse, my sister works in mental health, my mother worked at the hospital for 25 years, all due to her. It was all due to her.”