A Harford County man serving a six-year sentence for a sex offense was found dead in his cell at the Jessup Correctional Institution Wednesday, authorities said. Police believe his cellmate allegedly killed him.

Robert Joseph Tunnell, 21, formerly of Edgewood and Baltimore, was found dead in his cell with signs of trauma to his body and a string around his neck, police said.

While there is a known suspect in the case, charges are pending and police have not released the suspect's name.

Around 2 a.m. Wednesday, a correctional officer making routine rounds arrived at Tunnell's cell and Tunnell's cellmate allegedly said something to the officer that prompted an emergency response from staff, according to a statement from Maryland State Police. It was unclear Thursday what the nature of those statements was.

Tunnell wasn't responding when staff reached him and medical personnel were called. Medics pronounced Tunnell dead at the scene, the news release states.

According to state police, Tunnell's body showed signs of trauma and investigators found what looked like a shoe string around his neck.

The victim's body was taken to the Office of the Chief Medical Examiner in Baltimore for an autopsy to determine the official cause of death.

"It is a murder and there is a suspect who has been identified," state police spokesman Greg Shipley said Thursday.

Charges are pending against Tunnell's cellmate. In the meantime, the suspect remains in custody of the Maryland Division of Correction, according to state police.

The two men were being held in a transitional housing area usually designated for inmates brought in from other institutions or being moved for some reason.

"Tunnell was apparently serving a sentence at the Eastern Correctional Institution in Somerset," Shipley said, "I don't know why he was brought to JCI."

According to court records, Tunnell had a violation of probation hearing in Harford County the day before he was killed.

He was serving a six-year sentence after entering an Alford Plea on an attempted second-degree sex offense charge on March 12. An Alford Plea means the defendent acknowledges the state has enough evidence to convict, but maintains his innocence. It qualifies as a finding of guilt.

The underlying charges involved inappropriate contact with a boy, age 14, when Tunnell was 19 years old, according to court documents.