A man who admitted he was responsible for one of the worst cases of mass murder in Iowa history has hung himself in his prison cell.

In 2001 Adam Matthew Moss pled guilty to beating his girlfriend’s five children to death with a hammer while they slept, then hitting his girlfriend with the hammer before slitting her throat. Moss, who was 23 at the time, also killed a 58-year-old Sioux City businessman.

Joe Frisbie was Sioux City’s police chief at the time of the murders and he recalls the relief when Moss was captured after a brief manhunt.

“When we caught him, I never felt such relief in my life that we had this person off the street. It was a very scary situation for the whole community and I just remember it was like letting the air out of something,” Frisbie says. “I thought: ‘Thank God we have this person.'”

Frisbie says police who were at the crime scene were haunted by what they saw.

“I felt so bad for the officers that had to deal with that and carry that around with them. It was just horrible. It really was,” Frisbie says. “It just defies any explanation. There’s nothing you can say to try and figure out why a person would do that, you know, especially to little children.”

Moss had been separated from the general prison population and assigned to a room inside a unit for inmates with psychiatric problems. Iowa prison officials say he hung himself with a bed sheet Wednesday afternoon.

“As far as Adam Moss and what he’s done, the decision he made to take his own life, it’s hard to comment on that,” Frisbie says. “All’s I know is he went to prison for life and I was hoping that’s the way it would remain.”

Moss was sentenced to seven consecutive life prison sentences. He killed five children between the ages of six and 12 as well as his 31-year-old girlfriend and the 58-year-old man.

Reporting by Woody Gottburg, KSCJ, Sioux City