California Gov. Gavin Newsom (D) on Thursday denied parole for Sirhan Sirhan, the 77-year-old man convicted in 1969 of murdering Robert F. Kennedy.

“Mr. Sirhan’s assassination of Sen. Kennedy is among the most notorious crimes in American history,” Newsom said in a statement. “After decades in prison, he has failed to address the deficiencies that led him to assassinate Sen. Kennedy. Mr. Sirhan lacks the insight that would prevent him from making the same type of dangerous decisions he made in the past.”

In an opinion piece published Thursday afternoon in the Los Angeles Times, Newsom further explained that he carefully reviewed the case and examined historical records, and determined that Sirhan has “not developed the accountability and insight required to support his safe release into the community.” Sirhan is “a potent symbol of political violence,” Newsom wrote, and Kennedy’s assassination “not only changed the course of this nation and robbed the world of a promising young leader, it also left his 11 children without a father and his wife without a husband. Kennedy’s family bears his loss every day.”

Kennedy was shot and killed in June 1968 at the Ambassador Hotel in Los Angeles, shortly after he won California’s Democratic presidential primary. Sirhan, a Palestinian immigrant, claimed that he didn’t remember opening fire. He was originally sentenced to death, but this was commuted to life in prison when California briefly outlawed capital punishment in 1972.

A two-person state parole panel recommended in August that Sirhan receive parole. While two of Kennedy’s children said they supported his release, six others stated that they were upset by the recommendation.