JACKSON, Miss. (AP) — Another inmate has died in Mississippi, bringing the total to at least 15 in the state prison system since late December.

Jesus Garcia, 39, was found unresponsive in his cell Saturday at the Wilkinson County Correctional Facility, according to a statement from Management & Training Corporation, the private company that operates the prison.

A company spokesman, Issa Arnita, said in the statement Sunday that medical staff unsuccessfully tried life-saving measures, and the cause and manner of Garcia’s death are under investigation.

“There were no obvious signs of assault,” Arnita said.

Inmates have died at publicly run and privately run prisons in Mississippi since late December. Most died at the Mississippi State Penitentiary at Parchman, and many of their deaths came amid outbursts of violence.

More than two dozen inmates are suing the state over prison conditions.

Garcia was serving a 20-year sentence on a capital rape conviction from northern Mississippi’s DeSoto County, according to state Department of Corrections records. He was sentenced in 2006.