BESSEMER, Ala. (WIAT) — An inmate at William Donaldson Correctional Facility died on Tuesday after being treated for a disease in June.

Mark Len Johnson, 54, was taken to St. Vincent’s Hospital in Birmingham on June 12 for medical treatment regarding a natural disease he had been diagnosed with. He was pronounced dead at the hospital at 9:56 p.m. Tuesday. Johnson had been serving a life sentence for a 1993 murder conviction out of Sumter County.

The Alabama Department of Corrections Law Enforcement Services Division is investigating the circumstances surrounding the death. A postmortem examination will be conducted Wednesday to determine the cause of death.