An officer serving breakfast on Sunday found David Lee May unresponsive in his cell at the Central Mississippi Correctional Facility in Rankin County, the Mississippi Department of Corrections said. A department statement said officials tried to resuscitate the inmate, but he later was pronounced dead. Photo by Trip Burns

JACKSON, Miss. (AP) — A 42-year-old inmate has died in Mississippi, making him at least the 18th prisoner to die in the state's troubled prison system since late December, corrections officials said Sunday.

An officer serving breakfast on Sunday found David Lee May unresponsive in his cell at the Central Mississippi Correctional Facility in Rankin County, the Mississippi Department of Corrections said. A department statement said officials tried to resuscitate the inmate, but he later was pronounced dead.

According to the news release, there were no obvious signs of injuries. May was living by himself in a cell. He had been sentenced in 2017 to life for two aggravated assaults.

An autopsy is planned to determine the cause of death.

The death comes at a time of heightened scrutiny of Mississippi's troubled prisons system. The Justice Department announced Feb. 5 that its civil rights division was opening an investigation of Mississippi prisons after a string of inmate deaths.

At least 18 Mississippi inmates have died since late December. Most of them died at the Mississippi State Penitentiary at Parchman, and many were killed during outbursts of violence that also left an undisclosed number of inmates injured.