Sharon Tate's sister is doing everything in her power to ensure that a convicted murderer and follower of the infamous Manson family stays behind bars.

Debra Tate is lobbying California Governor Gavin Newsom to reject a move from the California Parole Board to release Leslie Van Houten, who was jailed for her part in the gruesome murder of Rosemary and Leno LaBianca in 1969 when she was 19.

The crime took place a day after Sharon and others were killed by members of the Charles Manson-led cult at her Los Angeles home. Van Houten was not present when Sharon and her unborn child were murdered.

In a letter to the Governor, obtained by TMZ, Debra doubts Van Houten’s rehabilitation, writing, “The danger of letting these people out of prison is ever-present and real. I am scared, not just for myself and other family members who may be targeted, but for society.”

SHARON TATE’S SISTER EXPLAINS WHY SHE’S GIVING AWAY STAR’S ICONIC WEDDING DRESS: ‘IT’S HARD TO LET GO’

Debra Tate, sister to actress Sharon Tate, is lobbying the governor of California to prevent the release of a member of the infamous Manson Family.

Debra Tate, sister to actress Sharon Tate, is lobbying the governor of California to prevent the release of a member of the infamous Manson Family. (Sarah Morris/Getty Images)

She goes on to reject the notion that Van Houten, who is now 70, has aged out of her criminal behavior.

“Age is immaterial to psychopathology,” Debra writes. “There is no cure for the sociopath. The disposition to committing violent crime does not have an expiration date. And criminals do not retire."

ANOTHER MANSON MURDER? DEBRA TATE, VICTIM'S SISTER, FIGHTS TO REOPEN PROBE INTO 1969 SUSPICIOUS DEATH

This March 29, 1971, file photo shows Leslie Van Houten in a Los Angeles lockup. She didn't take part in the Tate killings but accompanied Charles Manson and others to the LaBianca home the next night where she held Rosemary LaBianca down with a pillowcase over her head as she and others stabbed her dozens of times. 

This March 29, 1971, file photo shows Leslie Van Houten in a Los Angeles lockup. She didn't take part in the Tate killings but accompanied Charles Manson and others to the LaBianca home the next night where she held Rosemary LaBianca down with a pillowcase over her head as she and others stabbed her dozens of times.  (AP)

According to The Los Angeles Times, a California panel recommended Thursday that Van Houten be released after serving nearly five decades in prison. This is the fourth time that the former Manson Family member has been deemed fit for release. The decision ultimately falls on Newsom, who previously blocked her release once before. The other two release attempts were blocked by his predecessor, Gov. Jerry Brown.

“As with any parole suitability recommendation, when the case reaches the governor’s office, it will be carefully reviewed on its merits,” Vicky Waters, Newsom’s press secretary, said in a statement to the outlet.

The decision will fall to Newsom after a 120-day review process is concluded.

Leslie Van Houten attends her parole hearing at the California Institution for Women in Corona, Calif. California Gov. Gavin Newsom overruled a parole board's decision to free Charles Manson follower Leslie Van Houten.

Leslie Van Houten attends her parole hearing at the California Institution for Women in Corona, Calif. California Gov. Gavin Newsom overruled a parole board's decision to free Charles Manson follower Leslie Van Houten. (Stan Lim/The Orange County Register via AP)

CLICK HERE TO GET THE FOX NEWS APP

Manson died in 2017 from natural causes at a California hospital while serving a life sentence for ordering the murders of Tate, the other occupants of her house at the time as well as the LaBiancas.