OKLAHOMA CITY (AP) — An Oklahoma death row inmate awaiting execution for a 2004 slaying in Oklahoma City died of COVID-19, the Office of the Chief Medical Examiner said Thursday.

Nicholas Davis, 46, died on April 7 at a prison hospital in Lindsay after contracting the coronavirus, according to a medical examiner's report. Davis had several underlying health conditions, including inflammation of the lungs, an autoimmune disease and heart disease, according to the report.

Davis was housed at the Oklahoma State Penitentiary in McAlester awaiting execution for fatally shooting 17-year-old Marcus Smith. Prosecutors say Davis forced his way into Smith’s Oklahoma City apartment, fatally shot the unarmed man and wounded both Smith’s wife and Davis’ ex-girlfriend. Davis had exhausted all of his appeals, but an execution date had not been set.

According to the Department of Corrections, Davis is one of 56 inmates who have died of COVID-19 since the start of the pandemic last year.