McALESTER, Okla. (AP) - The Oklahoma Medical Examiner's office says a death row inmate found dead in his cell last month died of natural causes.

The Tulsa World reported Wednesday (http://bit.ly/1Q6FpjX ) that autopsy results show that 65-year-old Sammy Van Woudenberg had cardiovascular disease when he died March 5. 

Van Woudenberg had been convicted in 1983 for his role in the strangulation death of an inmate in the Muskogee County jail. He had been convicted previously of killing Oscar Louis Cates during a Tulsa party in 1973.

The newspaper reported that, in 1994, Van Woudenberg was found incompetent to be executed and ordered into psychiatric care. A judge said that if the inmate's mental health improved, he could be executed. The inmate's lawyer said Van Woudenberg took medication "intermittently" for schizophrenia.