A Philadelphia man who in 1989 murdered three gay men during a weeklong Center City killing spree died last week in a Pennsylvania prison, state officials said.

Arnold V. Mulholland, 50, was found unresponsive in his cell at State Correctional Institution-Mahanoy in Frackville, Schuylkill County, at 6:17 a.m. on Friday, according to a statement from the Pennsylvania Department of Corrections.

Mulholland was declared dead about an hour later, the agency said. The statement did not provide a cause of death, and the Schuylkill County Coroner's Office declined to release additional information without a right-to-know request.

In June 1989, he had been working as a gay prostitute in Center City when he killed three men in seven days, stabbing the men in their apartments after they invited him inside. Alexander Munchweiler, Tracy Griffin, and David Johnson, all were found dead or killed in early June, the news accounts said.

Alexander Munchweiler, a 61-year-old hairdresser, was found on the living room floor of his Walnut Street apartment with stab wounds to the chest, stomach, and arm. Days later, Mulholland stabbed David Johnson, a 58-year-old retired bank executive, more than 40 times inside an apartment on Spruce Street, a crime he confessed to his then-girlfriend. She also said she witnessed Mulholland stab Tracy Griffin in his Bainbridge Street apartment after stealing his bank card and forcing him to write a $100 check.

Mulholland was arrested later that month, after a fourth man, John Rowley, had managed to escape an encounter with Mulholland by jumping out a second-story window at 1900 Spruce St., breaking his back in the process. Following his arrest, Mulholland told police that gay men were "sick," but he broke down as he pleaded guilty in May 1990, choking back tears and slumping in his chair as his family members behind him sobbed.

He was sentenced to three consecutive life sentences.

The killings came during a months-long stretch in the region in which at least five other gay men were murdered, according to the Philadelphia Gay News.

Barbara L. Christie, the assistant district attorney on Mulholland's case, described him at the time as a "cool, cruel, calculating extinguisher of people." His own attorney, Perry de Marco Sr., said, "These were brutal, heinous killings," and added that Mulholland — who pleaded guilty to avoid execution — was sorry for "the havoc he created."

In an interview with the Inquirer published in 1993, Mulholland said: "I feel for the people. I regret it." But he did not remember the names or faces of his victims, and said he did not realize they had families — even though their relatives had shown up in court.