Authorities in Massachusetts on Monday concluded a woman whose mutilated body was discovered on Cape Cod nearly 50 years ago was killed by her husband.

The announcement by the Cape and Islands District Attorney Robert Galibois Monday brings to a close one of the state’s most famous cold cases. It was only in October that officials announced they had identified the woman, known as the “Lady of the Dunes,” as Ruth Marie Terry of Tennessee. She was 37 when she was killed in 1974 by what authorities concluded was blunt force trauma to the skull.

Since then, the focus has turned to Terry’s late husband, Guy Rockwell Muldavin, who had married her a few months before she disappeared. He was also a prime suspect in the death of another one of his wives and a stepdaughter in Seattle in the 1960s. Muldavin died in 2002.

After they married, state police learned that the couple had traveled to Tennessee to visit her family. “When Mr. Muldavin returned from that trip, he was driving what was believed to be Ms. Terry’s vehicle and indicated to witnesses that Ms. Terry had passed away,” Galibois said in a statement. “Ms. Terry was never seen by her family again.”

Based on the investigation into Terry’s death, authorities concluded Muldavin was the killer. They did not provide any more information on what was uncovered during the investigation.

The death of the “Lady of the Dunes” was one of the most enduring and frustrating murder mysteries in Massachusetts.

A young girl out for a walk found the body in the dunes in Provincetown in July 1974. The woman was naked on a beach blanket with her hands severed — so she could not be identified by her fingerprints, officials said. Her skull was crushed and she was nearly decapitated. The cause of death was determined to be a blow to the head and authorities believe she was killed several weeks before her body was found.

Joseph Bonavolonta, special agent in charge of the FBI’s Boston division, said at news conference in October that Terry, who was originally from Tennessee, was identified using investigative genealogy, the use of DNA analysis in combination with traditional genealogy research and historical records.

Terry, whose aliases included Teri Marie Vizina, Terry M. Vizina and Teri Shannon, also had ties to Michigan and California, authorities said.

She was the oldest unidentified homicide victim in Massachusetts. Authorities for decades tried to identify her and her killer by exhuming her remains, performing clay model facial reconstruction, and releasing age-regression drawings of her face.