Man Walks Into FBI, Confesses to 'Brutal, Ice-Blooded Murder' with Hammer Nearly 44 Years Later: Prosecutors

John Michael Irmer was arraigned in Boston on Monday on first-degree murder and aggravated rape charges related to the death of 24-year-old Pennsylvania woman Susan Marcia Rose (pictured), whose body was discovered in the city's Back Bay.

According to Suffolk County District Attorney's Office, her cause of death was determined at the time to be blunt facial injuries of the head with fractures of the skull and brain lacerations.

In a press release, the DA said Irmer "volunteered to agents" that he met a woman with red hair around Halloween -- on October 30 -- in Boston back in 1979. While the two met at a skating rink, he said they walked together to a building under renovation nearby, telling agents it was 285 Beacon Street in Back Bay. He then allegedly confessed to grabbing a hammer inside the building, striking the woman on the head -- killing her -- before raping her and fleeing to New York City the next day.

After his confession, investigators confirmed red-headed Susan Marcia Rose was discovered dead at the same address on the date in question. Irmer's DNA then matched samples preserved from the scene. According to CBS News, Irmer again confessed when interviewed by the Boston Police Cold Case Homicide Squad.

"Nearly 44 years after losing her at such a young age, the family and friends of Susan Marcia Rose will finally have some answers," District Attorney Kevin Hayden said in a 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. No matter how cold cases get resolved, it’s always the answers that are important for those who have lived with grief and loss and so many agonizing questions,."

Another man was tried and cleared of her murder in June 1981.

Investigators say Irmer previously served 3 decades in prison for another homicide in California -- and allegedly admitted to another murder in a southern state while confessing about Rose, a claim authorities are investigating. He had been free for about 10 years before his apparent confession.