BOSTON (AP) — A 68-year-old man walked into an FBI field office in Portland and confessed to bludgeoning a woman to death more than four decades ago in Boston’s Back Bay neighborhood, prosecutors said.

John Michael Irmer, 68, was arraigned Monday in Boston.

John Michael Irmer of Portland stands during his arraignment in Boston for the 1979 murder of Susan Marcia Rose, September 11, 2023 (KOIN)
John Michael Irmer of Portland stands during his arraignment in Boston for the 1979 murder of Susan Marcia Rose, September 11, 2023 (KOIN)

At the arraignment, Suffolk County Assistant District Attorney John Verner said, “They were walking up the stairs of the building when the defendant, Mr. Irmer, picked up a hammer and beat her in the head with it.”

Irmer, who prosecutors say is also being looked at after allegedly confessing to another slaying, was ordered held without bail pending another court appearance on Oct. 17 on charges of first-degree murder and aggravated rape.

Investigators said Irmer had been free for 10 years after serving three decades in prison for a homicide in California. He told FBI agents in Portland, Oregon, last month that he’d met a woman with red hair — identified as Susan Marcia Rose — at a skating rink just before Halloween in Boston in 1979.

“A few days later, detectives from the Boston Police Cold Case Homicide Squad flew out to Portland Oregon after reviewing the file and spoke to Mr. Irmer who, again, confessed to what he did,” Verner said.

Irmer said the two walked around the Back Bay before entering an apartment building that was under renovation at the time, prosecutors said. Just after entering the building, Irmer told investigators, he grabbed a hammer and struck Rose on the head, killing her. He then raped her and fled to New York the next day.

Susan Marcia Rose, killed in Boston in 1979, seen in an undated photo (Courtesy photo)
Susan Marcia Rose, killed in Boston in 1979, seen in an undated photo (Courtesy photo)

Steven Sack, the attorney representing Irmer, said he wouldn’t contest bail, but highlighted Irmer’s decision to turn himself in.

“I would say on his behalf, he was a free man for 10 years. He walked into police and confessed, allegedly,” Sack said.

Another man had been arrested by police at the time and charged with the crime, but was acquitted in 1981 of the charges.

Police said Rose, who had red hair, was found dead in the building on Oct. 30, 1979. The cause of death was determined to be blunt injuries on the head with skull fractures and lacerations of the brain.

Investigators also took a DNA sample from Irmer, which they said turned out to be a match with DNA samples preserved from the murder scene.

Rose had moved to Boston from Johnstown, Pennsylvania and was living on a nearby street at the time of her death.

“Nearly 44 years after losing her at such a young age, the family and friends of Susan Marcia Rose will finally have some answers,” Suffolk District Attorney Kevin Hayden said in a written statement.

“This was a brutal, ice-blooded murder made worse by the fact that a person was charged and tried — and fortunately, found not guilty — while the real murderer remained silent until now,” he added.

KOIN 6 News reporter Jami Seymore contributed to this report.