ROCKFORD — Asphyxiation by hanging has been ruled the cause of death of a 19-year-old man found deceased early Saturday inside a Winnebago County Jail cell.

The autopsy was performed Monday, and the results were released Tuesday by Winnebago/Boone Integrity Task Force Commander Sam Thomas.

"Members of the Winnebago/Boone Integrity Task Force continue to garner information in this investigation, but circumstances surrounding this incident indicate that Matthew’s injuries were self-inflicted, alluding to an apparent suicide," Thomas said.

Justin T. Matthews was arrested on murder charges in connection to the Dec. 22, 2016, stabbing death of Brian Abbott, 21, of Racine, Wisconsin. Abbott was pronounced dead at the scene near 10th Street and Sixth Avenue in Rockford. An autopsy showed Abbott died of multiple puncture wounds.

Matthews was booked Sept. 8 into the Winnebago County Jail and was being held on $3 million bond.

Investigators think Matthews' death occurred between 5 and 5:15 a.m. Saturday when corrections officers found him unconscious in his cell. Jail Superintendent Bob Redmond said corrections officers and nursing staff started CPR until the arrival of Rockford Fire Department paramedics. He was pronounced dead at 5:50 a.m.

Matthews was the only person in the cell at the time of his death, Thomas said. Inmates are regularly locked in their cells overnight from 10:30 p.m. to 6:30 a.m.

No other details about the death were released.

Because Matthews died in custody of the Winnebago County Jail, Sheriff Gary Caruana requested an investigation by the Integrity Task Force.

Chris Green: 815-987-1241; cgreen@rrstar.com; @chrisfgreen