In November (15), the former child star, who voiced characters in Peanuts TV specials, pleaded guilty to sending letters to a number of recipients offering to pay money to have San Diego County Sheriff Bill Gore killed.

He also admitted sending threatening letters to the manager of the mobile home park where he lived in Oceanside, California.

Robbins appeared in a San Diego, California court on Monday (07Dec15) and his lawyer Joey Super asked to withdraw the guilty plea, but the request was denied.

Los Angeles Superior Court judge William Chidsey, Jr. sentenced Robbins to four years and eight months in prison.

Robbins, 59, previously revealed he suffers from bipolar disorder and paranoid schizophrenia.