A man serving a life sentence for a 2003 murder in Fulton County died Saturday after an altercation with another inmate in a South Georgia prison, according to the state Department of Corrections.

Thomas McCoy was an inmate at Ware State Prison in Waycross and his death is now under investigation, the agency said. No details were released about the cause of death, pending an autopsy to be conducted by the GBI.

“The facility remains on lockdown, the length of which will be at the discretion of the warden,” a GDOC spokeswoman said in a statement.

McCoy was tried twice and convicted both times, along with a co-defendant, in the murder of 42-year-old Theodore Barber.

Barber was shot and killed on Dec. 2, 2003, inside his Welcome All Road apartment in south Fulton County. He called 911 to report two men attempting to kick in his front door, and the 911 recording captured the sound of the door being knocked in and shots fired.

McCoy and Michael Favors, who had gone to the apartment complex intending to rob someone, left in separate vehicles but were quickly taken into custody, according to the Fulton County District Attorney’s Office.

In 2005, McCoy and Favors were both convicted and sentenced to life in prison. A motion for a new trial was granted in 2011, and the retrial ended with a second conviction in April 2012.

Both men were convicted of murder, felony murder, aggravated assault with a deadly weapon, burglary, theft by receiving a stolen vehicle and possession of a firearm during the commission of a felony.

Following their 2012 convictions, each man was sentenced to life plus five years in prison by presiding Superior Court Judge Robert McBurney. Favors is an inmate at Hays State Prison in Trion, according to the GDOC.