SAN DIEGO -- A former child actor who was the voice of Charlie Brown in beloved "Peanuts" TV specials was sentenced to nearly five years in prison Monday for making criminal threats.

Peter Robbins, 59, pleaded guilty last month to sending threatening letters to a manager at a mobile home park in suburban Oceanside, where he lived.

He also sent letters to members of the media in which he offered to pay money to have San Diego County Sheriff Bill Gore killed.

Prosecutors said he also threatened a San Diego judge, but that charge was not part of a plea agreement.

Peter Robbins in court. CBS affiliate KMFB

Robbins, who made numerous outbursts in earlier hearings, was relatively subdued at his sentencing, according to The San Diego Union-Tribune.

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His attorney, Joey Super, made a request on his client's behalf to withdraw his plea.

William Chidsey Jr., a retired Los Angeles Superior Court judge who was brought in to handle the case after San Diego judges recused themselves, sentenced the former actor to four years and eight months in prison.

Robbins has said he has bipolar disorder and suffers from paranoid schizophrenia.

From age 9 to 13, Robbins was the voice of Charlie Brown in a series of 1960s animated classics, including "A Charlie Brown Christmas" and "It's the Great Pumpkin, Charlie Brown."

Two years ago, Robbins pleaded guilty to threatening a former girlfriend and her plastic surgeon.