Infamous Alaska serial killer Robert Hansen died Thursday morning at an Anchorage hospital, according to the Department of Corrections.

Hansen died around 1:30 a.m. at Alaska Regional Hospital, Sherrie Daigle, deputy director of administrative services for the Department of Corrections, said. He had been transferred to the hospital on Wednesday. Cause of death will be determined by the medical examiner, but it appears he died of natural causes, she said. He had been in declining health for the past year, according to a press release.

"On this day we should only remember his many victims and all of their families and my heart goes out to all of them," wrote Glenn Flothe, retired Alaska State Trooper who was instrumental in Hansen's capture.

"As far as Hansen is concerned, this world is better without him." Flothe wrote. "It's a sad day for me, for their families."

Hansen had been moved from the Spring Creek Correctional Center in Seward to the Anchorage Correctional Complex on May 11, Alaska Dispatch reported at the time. Hansen, 75, had been placed in medical segregation in Anchorage, which is akin to being in the hospital, Daigle said then. Anchorage's jail is one of the state's only correctional facilities with a medical unit.

Hansen had received a 461-year sentence in February 1984, pleading guilty to the murder of four women. Hansen had confessed to authorities that he had killed 17 women and raped another 30 women over more than a decade.

"He will not be missed," said Frank Rothschild, the assistant district attorney who tried the case, from Hawaii on Thursday afternoon. "Good riddance to him."

"He's one of those kind of guys that you kind of hope every breath he takes in his life, there's some pain associated with it, because he caused such pain," Rothschild added.

The infamous murderer lured topless dancers and prostitutes in downtown Anchorage with money. Hansen would kidnap the women at gunpoint, tie them up, then fly to remote areas to kill his victims.

A turning point came in 1983, when a teenage prostitute named Cindy Paulson ran into a Fifth Avenue motel in handcuffs, saying that Hansen had imprisoned her at his home, raped her and put her on his plane for a one-way ride.

Several months later, police armed with several search warrants went through Hansen's home, finding enough evidence to eventually charge him with four murders. As part of his plea deal, Hansen agreed to help authorities find the graves of the murdered women. Only a dozen bodies were located.

Rothschild recounted watching Hansen transform into "the monster he was" the day prosecutors sat down with Hansen and laid out the evidence they had against him. They told Hansen they had his own map marked with 17 locations that they believed indicated the locations of bodies.

"He was mild-mannered Bob the Baker, and as I'm looking at him, all of sudden he transformed. The hair on the back of his neck stood up and his neck got red, and he was pissed.

"I can still see him when he got livid like that," Rothschild said.

Hansen asked to speak with his attorneys and went out into another room. "You could hear him screaming at his lawyers," Rothschild said.

Rothschild worked as a district attorney in Anchorage for only three years. His wife at the time had asked that at some point, he take some time off so they could go traveling. "When the Hansen case was over ... I was ready," Rothschild said. "It was just so heavy to see what this human being was capable of doing."

Hansen didn't see his victims as human, Rothschild said. "In his mind there were good girls and bad girls. These were all purposefully bad girls."

Hansen's sentence began in Pennsylvania, but he returned to Alaska in 1988. Hansen was one of the first prisoners at the newly opened Spring Creek Correctional Center, where he had remained since.

During much of his time at Spring Creek, Hansen worked as a barber, but he had not held a job in the facility for many years, Daigle wrote. He had several cellmates during his decades at the facility, was well-behaved and was considered a low-maintenance prisoner, Daigle wrote.