MINNEAPOLIS — A mentally ill patient at the Minnesota Security Hospital who has a history of violent behavior was in custody Thursday, accused of killing another patient who died after hospital staff found him in his room, badly injured.

St. Peter police said 41-year-old Michael Francis Douglas, a convicted murderer, was found in his room Wednesday night as staff members were conducting routine checks. Police arrived and “discovered Douglas lying in his room with what appeared to be injuries caused by violent trauma,” a police statement said.

Paramedics’ attempts to save him were unsuccessful.

A 31-year-old man was arrested and booked into the Nicollet County Jail and is suspected of murder. Formal charges were pending.

St. Peter police Chief Matt Peters said both men were patients at the security hospital, which is the state’s largest psychiatric facility and serves people who are committed as mentally ill or mentally ill and dangerous. The Department of Human Services said there are nearly 400 patients at the hospital.

Deputy Human Services Commissioner Anne Barry said in a statement that the department is doing everything it can to assist law enforcement and was reaching out to the victim’s family, patients and employees who were affected by the tragedy.

Barry said the Department of Health and the ombudsman for Mental Health and Developmental Disabilities would be reviewing the deaths. A joint commission that accredits health care organizations is also analyzing how something like this could have happened.

Peters said he couldn’t elaborate on the nature of Douglas’ injuries, or say whether a weapon was found as authorities were still investigating. He also couldn’t say why these men were in the security hospital, citing medial privacy rules.

But according to court records, both men were committed last year.

The suspect suffers from paranoid schizophrenia that “has severely-disordered his thought process resulting in bizarre and aggressive behaviors,” according to his commitment order in Beltrami County District Court.

He was committed in October for a period of six months as a mentally ill person, after a judge found him incompetent to stand trial on a burglary charge.

He also has a prior history of violence. According to the Star Tribune, he admitted in federal court to stealing a pickup truck from two Red Lake band members at knifepoint in 2001. That same year, he also admitted to kicking in the door of a home on the reservation and bashing a man in the head with a metal pipe.

Douglas was committed in December as mentally ill and dangerous.

According to court documents from Blue Earth County, Douglas and an accomplice tied up a man and killed him with a hammer during a 1991 burglary. He had been in prison from 1992 to January 2013, but was brought back into jail for violating terms of his provisional release. He had problems taking his medication and had made aggressive and threatening statements that led to his commitment, court documents show.

The Minnesota Security Hospital has had a series of management lapses in recent years.

Human Services Commissioner Lucinda Jesson placed the hospital on conditional license status in 2011 after reviewing several cases of patient maltreatment, and Gov. Mark Dayton said the hospital was in “crisis” after he visited in 2012.