DNA and genetic genealogy have linked a Navy man to the 1984 murder of his classmate, 25-year-old Pamela Cahanes, authorities announced Thursday.
Two days after graduating from U.S. Navy basic training -- which was held in the Orlando area at the time -- Cahanes was found beaten and strangled to death, Seminole County Sheriff Dennis Lemma told reporters Thursday.
Cahanes' mostly nude body was discovered the morning of Aug. 5, 1984, near a vacant home in unincorporated Sanford, Florida, Lemma said.
Thomas Lewis Garner, who was Cahanes' classmate at the Navy's training center, was arrested Wednesday for her first-degree premeditated murder, sheriff's office spokesman Bob Kealing told ABC News.
The two were known to each other, Kealing said.
The sheriff's office said it's unclear how long Garner, 59, served in the Navy. A Navy spokesman did not immediately respond to ABC News' request for comment.
Though Lemma said DNA has definitively linked him to the scene, Garner, of Jacksonville, has denied involvement, according to the sheriff.
Investigators used genetic genealogy to build a family tree that matched Garner to DNA found on Cahanes, the Seminole County Sheriff’s Office said.
Genetic genealogy takes the DNA an unknown killer left behind at a crime scene and identifies the suspect through his or her family members, who voluntarily submit their DNA to genealogy databases. This allows police to create a much larger family tree than using DNA submissions to law enforcement databases, in which an exact match to the suspect is needed in most states, according to CeCe Moore, chief genetic genealogist with Parabon NanoLabs, which she says has worked on the majority of the cases, including Cahanes'.
The first public arrest through genetic genealogy was the April 2018 identification of the suspected "Golden State Killer." Since then, genetic genealogy has helped identify more than three dozen suspects in violent crimes, said Moore.
Cahanes is survived by many siblings but her mother died before the arrest was made and "never had the opportunity to see this," Lemma said.
Officials at the Naval Criminal Investigative Service (NCIS) "never lost sight of the fact that the family of Recruit Pamela Cohanes needed to know as much as possible about what happened to her,” NCIS Special Agent in Charge Matthew Lascell said in a statement Thursday.
“It's gratifying to have been part of discovering the truth," Lascell said.
Garner is set to appear in court Friday, Kealing said. He has not entered a plea and is being held on no bond, Kealing said.
ABC News' Olivia Rubin contributed to this report.