Mass murderer Charles Manson was denied parole in his 12th and probably final bid for freedom.

Manson, now a grey-bearded 77-year-old, did not attend the California hearing where the parole board ruled he had shown no efforts to rehabilitate himself. He is not eligible for parole for another 15 years.

"This panel can find nothing good as far as suitability factors go," said John Peck, a panel member.

A key factor in the board's decision was something Manson said recently to one of his prison psychologists, which Peck read aloud: "'I'm special. I'm not like the average inmate. I have spent my life in prison. I have put five people in the grave. I am a very dangerous man.'"

The panel deliberated for 20 minutes before making its decision.

Manson orchestrated a series of gruesome murders that terrified Los Angeles 40 years ago. Manson and his followers were convicted for the 1969 slaying of actress Sharon Tate and four others.

No clear motive was ever established. Manson was sentenced to death, but his life was spared when the California supreme court briefly outlawed the death penalty in 1972.

"I'm done with him," Debra Tate, the sister of the actress, said after the hearing.

Under the law, inmates can be denied the chance to reapply for parole for up to 15 years. Manson would be 92 before gets another opportunity to make his case.

Authorities read a litany of Manson's prison infractions, including the latest – manufacture and possession of a weapon, for which he is serving 15 months in an isolation unit.

"It's obvious from everything in the record that Mr. Manson remains a danger to the public," said deputy district attorney Patrick Sequeira, who argued against parole.

Even Manson's state-appointed attorney, DeJon Lewis, found it difficult to argue for a client who had refused to meet with him. He said at the hearing that Manson should be in a hospital, but he acknowledged the terror his client caused.

"The murders showed us that anyone could be killed at any time, and no one was safe, not even at home," Lewis said.

Manson, however, is anything but a recluse. He has a steady stream of visitors, including college students writing papers about him, said Theresa Cisneros, spokeswoman for Corcoran state prison. Manson must approve all requests.

"He has a large interested public," Cisneros said, adding that Manson received more mail than most prisoners.