On the morning of September 4, 1981, police responded to an apartment in Lakeland, Florida, to find a grisly scene.
Linda Patterson Slaten, 31, was found strangled to death with a coat hanger twisted around her neck. She was partially nude. According to court documents obtained by ABC News, a window screen had been removed from her bedroom. It was presumably the access point where the killer had entered the home.
Most disturbing: The woman’s two sons, 15-year-old Jeff and 12-year-old Tim, were asleep in the other room.
For nearly 40 years, the sons have dealt with the emotional fallout from that tragic night. “I saw the crime scene. It’s still burned in my brain today,” Tim Slaten said at a Thursday news conference.
Tim Slaten told authorities that his football coach, Joseph Mills, had driven him home the night before. Authorities interviewed Mills but did not consider him a suspect at that time. They recovered semen from the crime scene and years later, when DNA testing became a routine tool for law enforcement, the semen was analyzed — but it matched no one in law enforcement databases.
Frustratingly, the case went cold, and it appeared that the murder would never be solved.
“It’s been rough on me my whole life not knowing who it is,” Jeff Slaten said at the news conference, ABC News reports. “Always being scared to death I was friends with him. Always looking over our shoulder.”
The case remained an open investigation. Then, in 2018, the Florida Department of Law Enforcement called the Lakeland Police Department and asked if they wanted to send DNA from the crime scene for further testing.
According to the Tampa Bay Times, the DNA was sent to Parabon Nanolabs, where they matched the DNA through public genealogy databases. These databases are populated by the DNA of family members who voluntarily upload their DNA.
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The resulting report indicated that the person who most likely killed Slaten was Joseph Mills, according to an arrest affidavit filed with the Polk County Clerk of Courts.
Joseph Mills, now 58, was arrested by Lakeland Police Department detectives on Dec. 12. PEOPLE confirms that he has been charged with first-degree murder, sexual battery and burglary with assault and battery. He was 20 years old in 1981, when Slaten was killed.
According to court documents, Mills told police that he had consensual “wild” sex with Slaten, but denied having killed her. But police believe that he is responsible for her death, and court documents claim that the scene indicated signs of a struggle.
The arrest has left Slaten’s family reeling: “He was my football coach,” Tim Slaten, now 50, told reporters on Thursday, according to The Ledger. “I trusted this man.”
Mills has not yet entered a plea and will be arraigned on January 21. The public defender’s office did not immediately return PEOPLE’s call for comment.