CHICAGO (STMW) — A South Carolina man charged with murder died last week while in custody at the federal Metropolitan Correctional Center downtown.

Albert Leon Bowen, 64, was in the custody at the prison at 71 W. Van Buren St. when he was transferred to Thorek Hospital on Dec. 19, according to the Cook County medical examiner’s office and a statement from the U.S. Marshals Service. He died at the hospital at 4:26 a.m. Jan. 6.

Preliminary cause of death is believed to be natural “due to massive organ failure,” according to a statement from the U.S. Marshals Service. An autopsy is scheduled for Tuesday.

Bowen was charged in September 2015 with two counts of murder for the shooting deaths of two men in Pickens, South Carolina, according to a statement from the Pickens County sheriff’s office. He was later charged by the ATF with being a felon in possession of a firearm in Greenville, South Carolina.

The Belton, South Carolina, resident had been in Chicago since October 2015 in the custody of the U.S. Marshals Service undergoing psychiatric evaluation in advance of an upcoming trial, the sheriff’s office said.

The sheriff’s office said he was in the process of going back to South Carolina when he “suffered a health issue.” His death remains under investigation by the Marshals Service.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2016. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)