Woody Harrelson's father, Charles, died in prison last week.
Charles Harrelson, 69, had been serving two life sentences in a maximum-security Colorado federal prison for the 1979 slaying of a federal judge.
He was found unresponsive in his cell on March 15, Felicia Ponce, a Bureau of Prisons spokeswoman in Washington, told the Associated Press. Fremont County Coroner Dorothy Twellman said he probably died of a heart attack in his sleep.
Harrelson was convicted in 1982 of the slaying of a federal judge in San Antonio, Texas, in what prosecutors described as a $250,000 contract murder. Harrelson maintained his innocence and appealed in 1998
, but the conviction was upheld.
Woody Harrelson's rep was not immediately available for comment.
The actor was just 7 when the elder Harrelson was first jailed, for killing a Texas businessman, the AP reports. He was in college when his father was convicted of the judge's assassination.