A Clayton County jail inmate was charged Thursday with killing his cellmate, authorities said.

According to Clayton County Sheriff's Office spokesman Capt. Brian Crisp, William Alexander Brooks was charged with malice murder and aggravated battery for fatally beating Kenneth Robert Grochowski late Tuesday night or early Wednesday morning in their cell.

Jail staff noticed Grochowski, 57, unresponsive around midnight following roll call, Sheriff Kem Kimbrough said.

Grochowski was taken to Southern Regional Medical Center, where he was pronounced dead around 4 p.m., Kimbrough said.

Brooks, 21, had been in the jail since Aug. 1, when he was arrested on theft by receiving stolen property charges after Forest Park police pulled him over driving a stolen 2002 Nissan Quest, authorities said.

Brooks was also wanted for violating his probation on burglary charges in Bay County, Fla., Crisp said.

Grochowski was a fugitive from Illinois who was wanted for 2007 weapons, eluding police and DUI charges. Crisp said he was arrested Aug. 8 when he landed at Harstfield-Jackson International Airport on a flight arriving from South America.

Kimbrough told Channel 2 Action News that no rules prohibit an inmate from being place in a jail cell with another adult inmate half his age.

The GBI performed the autopsy on Grochowski's body and assisted with the investigation, sheriff's officials said.