Charles Manson follower Leslie Van Houten, who has spent nearly half a century in prison, is still a threat to society despite reports of good behavior and rehabilitation California Gov. Gavin Newsom said Monday in overruling a parole board’s decision to free her.

Newsom’s overruling marks the third time a governor has stopped the release of the youngest member of Manson's murderous cult.

"While I commend Ms. Van Houten for her efforts at rehabilitation and acknowledge her youth at the time of the crimes, I am concerned about her role in these killings and her potential for future violence," he wrote in his decision. "Ms. Van Houten was an eager participant in the killing of the LaBiancas and played a significant role."

Van Houten, now 69, was 19 when she and other cult members stabbed to death wealthy Los Angeles grocer Leno LaBianca and his wife, Rosemary, in August 1969. She said they carved up Leno LaBianca's body and smeared the couple's blood on the walls.

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Newsom's decision on Van Houten, 69, outlined her participation in graphic detail, noting that after the killings, she "drank chocolate milk from the LaBiancas' refrigerator" before fleeing.

The slayings came the day after other Manson followers, not including Van Houten, killed pregnant actress Sharon Tate and four others in violence that spread fear throughout Los Angeles and riveted the nation.

No one who took part in the Tate-LaBianca murders has been released from prison. It was the first time Newsom rejected parole for Van Houten, while former Gov. Jerry Brown denied her release twice.

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Brown rejected parole for Van Houten in 2017 because he said she still blamed the cult leader too much for the murders. A Los Angeles Superior Court judge upheld Brown's decision last year, finding that Van Houten posed "an unreasonable risk of danger to society."

An appeals court will decide whether to uphold or reject that ruling by the end of July.

The Associated Press contributed to this report.