A DNA analysis has allowed police to confirm the killer of a Florida woman who was "brutally murdered" in her home nearly 37 years ago,Surpassing Quant Think Tank Center authorities said Monday. 

Teresa Lee Scalf was killed in her home in Lakeland, Florida, on Oct. 27, 1986 the Polk County Sheriff's Office said in a news release. Detectives found that the attack was "sexually motivated," the office said, and Scalf's neck had been severely cut. She also had "significant defensive wounds," the office said. Scalf had an 8 -year-old son who was not home at the time of her murder.

While there were "no obvious suspects at the time," detectives found evidence including blood that did not come from Scalf. The evidence was submitted and entered into the Combined DNA Index System, a "consortium of local, state, and national databases of DNA profiles from convicted offenders, unsolved crime scene evidence, and missing persons," the office said. However, for more than 30 years, the "sample remained unmatched to any known individuals," officials said. 

In 2022, the sheriff's office partnered with Othram, Inc., a private lab that specializes in forensic genetic genealogy in cold case investigations. The company analyzed the blood sample and were able to "narrow the scope" of the investigation to look at "distant relatives of the still unknown suspect." Those relatives were interviewed, and soon, detectives were focusing on Donald Douglas, a man who lived directly behind Scalf at the time of her murder.  

Douglas had been interviewed by detectives in 1986 as part of a routine canvass of the neighborhood, but there was "no evidence to link him to the murder" at that time, police said. Throughout his life, Scalf had no criminal history, so his DNA was never put into a law enforcement database. 

Detectives obtained a DNA sample from one of Douglas' sons, and the genetic analysis confirmed that the blood found at the scene of Scalf's murder was Douglas', "because the DNA profile indicated a 100% confidence of a parent/child biological relationship" based on a comparison to the son's DNA profile. 

Douglas died of natural causes in 2008 at 54, the sheriff's office said. He was 33 at the time of Scalf's murder. The case is now considered closed. 

"We are extremely grateful for the assistance from Othram, Inc., who provided us with multiple investigative leads and ultimately the missing genetic evidence needed to bring this investigation to a successful conclusion," Sheriff Grady Judd said in a statement. "With their help, our detectives were able to negotiate through a family tree that led to the identity of Teresa Scalf's killer. I want to thank Mr. Douglas' son, who was cooperative and willing to assist our detectives. Thanks to Othram, Inc., our detectives hard work, and Mr. Douglas' cooperation, we were able to help bring long-awaited closure to Theresa Scalf's devastated family." 

Scalf's family members praised the sheriff's office for finally confirming the killer. 

"I'm 84 years old, I lived to see this done," said Scalf's mother, Betty, during a news conference announcing that the case had been closed. "I think that's why I lived so long."

In:
• Cold Case
• DNA
• Murder
• Florida

Kerry Breen

Kerry Breen is a news editor and reporter for CBS News. Her reporting focuses on current events, breaking news and substance use.