Charles Harrelson attempted to break out of prison in 1995

Charles Harrelson, 69, was found dead in his cell on 15 March, apparently of natural causes, authorities confirmed.

He was convicted in 1982 of shooting US District Judge John Wood on a contract from a drug dealer who was facing trial in the judge's court.

Harrelson denied the killing, and his son supported several attempts to overturn the conviction.

He was transferred to Supermax, the highest-security federal prison in the US, after attempting to break out of an Atlanta federal prison in 1995.

Fremont County coroner Dorothy Twellman said an autopsy showed Harrelson had severe coronary artery disease, and probably died in his sleep.

Woody Harrelson first came to attention as Woody the bartender in the hit TV sitcom Cheers.

He went on to star in films such as White Men Can't Jump and The People Vs Larry Flint, and had a recurring guest role in comedy series Will and Grace.

The actor was just seven years old when his father was first sent to prison, for murdering a Texas businessman.

He was in college when his father was convicted of the judge's assassination.