 -- The sister of Sharon Tate says Leslie Van Houten, the “Manson family” member who was just recommended for parole, is a “monster” who is “still capable of great brutality.”

“I sit as far away from her as you and I are now. You can feel the vibe,” Debra Tate told Robin Roberts today on “Good Morning America.”

Tate, 63, was present at the five-hour hearing last week in Chino, California, that led to the recommendation that Van Houten, 66, be eligible for parole.

“They are still sociopathic individuals and capable of great brutality,” Tate said of Van Houten and other members of the Manson cult. “The heinous crimes that were committed in the past, in 1969, will repeat themselves again. I am quite sure.”

Van Houten was 19 and the youngest Manson follower when her time in Manson's cult turned deadly and she participated in the Aug. 10, 1969, murders of Leno LaBianca, a wealthy grocer, and his wife, Rosemary LaBianca.

She did not participate in the Aug. 9, 1969, "Manson family" murders of Sharon Tate and four others in the California home Tate shared with her husband, film director Roman Polanski. Tate was 26 and pregnant at the time of her murder.

The group imagined the series of murders would ignite a so-called race war ignited by Manson. Manson called it "Helter Skelter."

Debra Tate has appeared at every parole hearing for every “Manson family” member since the murders. She described what it was like to hear that Van Houten may go free after more than four decades behind bars.

“Your heart sinks between your knees,” Tate said. “It’s absolutely mind-boggling what goes through your mind. All of the atrocities from the past, the brutalities all come flooding back.”

Van Houten’s parole is not guaranteed. The decision next goes to an administrative review and, if it is upheld, it then goes to California Gov. Jerry Brown, who has final say.

Brown earlier this year denied the parole recommendation for Manson follower Bruce Davis, which Tate says gives her “solace.”

“That’s our only solace, that he will stop this parole in the case of Van Houten,” Tate said. “This is a slippery slope and it’s going to be all of our problems because six months on parole and they’re free to go anywhere in the United States.”

Tate added, “It’s not just California’s problem. It’s the United States’ problem.”

Tate has also started a website with a petition to get signatures to send to Gov. Brown.

“These people are domestic terrorists and when they’re released they can go anywhere in the United States,” Tate said. “Parole isn’t even the catch-net. We have to stop this before it happens.”

ABC News' Emily Shapiro contributed to this report.