MADISON, Wis. -- The former University of Wisconsin-Madison student convicted of killing Madison resident Joel Marino last year apparently committed suicide on Saturday night while serving a life sentence in the Dodge Correctional Institution in Waupun, according to Dodge County authorities.

READ: Marino's Family Reacts To Peterson's Death | VIDEO: Watch The Report

Adam C. Peterson, 20, apparently hanged himself and was found by his cellmate. Peterson was discovered hanging from an upper bunk bed railing shortly after 10 p.m. One end of a bed sheet was tied around his neck and the other tied to the railing of the bed, according to the Dodge County Sheriff's Department.

Peterson’s cellmate alerted prison staff, who immediately attempted emergency measures until paramedics arrived. He was pronounced dead at the prison at 10:21 p.m. Authorities said that Peterson had entered DCI on Dec. 8 "to undergo his initial assessment and evaluation."

The sheriff's department and DCI are investigating the death. They said that they don't suspect foul play.

Peterson was accused of fatally stabbing Marino in his home last January in what authorities believe was a robbery attempt. Last month, Peterson entered a guilty plea to one count of first-degree intentional homicide during a hearing in Dane County Circuit Court. Peterson is a Stillwater, Minn., native who dropped out of the University of Wisconsin-Madison last year.

Peterson was sentenced to life in prison, but a separate trial within the next few months will decide Peterson's true fate. Prosecutors told the court that they will recommend no more than 40 years behind bars before Peterson could be eligible for release.

Joel Marino, 31, was a musician and technical representative for a medical device company.

Peterson had apparently attempted suicide before while being held in jail awaiting trial and prior to entering the guilty plea.

Peterson's attorney, assistant public defender Dennis Burke, said that since Peterson was moved to the facility in Waupun, he was "doing better" and was more at "ease with his surroundings."

"It's very difficulty to make sense of what happened," he said.

Burke had told the court last month that his client had a rough go in jail and he was "anxious to move on to prison." Burke had said that his client is suffering from mental illness but was able to tell right from wrong when he stabbed Marino to death.

A state Department of Corrections official spoke about Peterson's state of mind as he served his time.

"He had been adjusting in the unit he was in. He was not under suicide watch," said DOC spokesman John Dipko. "Questions about signs and possible signs, whether or not there were clues that this could've happened, that all needs to be part of the review that we will undertake."

Dipko said the DOC is assisting the Dodge County Sheriff's Department with its investigation. He said the department will then focus on an internal review of the incident by looking at documents and talking with staff.

One of Marino's friends expressed disbelief on Sunday at the news of Peterson's death.

"I'm shocked," said Joel's best friend, Bryan Bazan. "This is very disappointing."

Bazan said he wanted to see Peterson spend the next 40 to 50 years in prison for what he did to his friend.

Stay tuned to WISC-TV and Channel 3000 for continuing coverage.