(CNN) -- A former CBS news producer who was convicted of attempting to extort money from late-night television host David Letterman over an affair with a colleague was released from prison Thursday.
Robert "Joe" Halderman was released from the Rikers Island facility after serving four months of his six-month sentence, according to the New York City Department of Corrections. He was let out early for good behavior, said spokesman Steve Morello.
Halderman was sentenced May 4. He pleaded guilty in March to attempted second-degree larceny in exchange for the promised sentence of six months in jail, five years' probation and 1,000 hours of community service.
Halderman, who was a producer for "48 Hours," admitted that he tried to extort $2 million from Letterman in exchange for keeping quiet about Letterman's affairs with female staffers.
The prosecutor said Letterman, through an attorney, gave Halderman a $2 million check last year and Halderman deposited the money into a Connecticut bank account the day before he was arrested.
Letterman announced the extortion plot on his CBS show in October and admitted he had affairs with female staffers.
Appearing in court in May for his plea, Halderman expressed "great remorse" and apologized to Letterman and his family as well as the family of Stephanie Birkitt, one of the women Halderman named as having had a sexual relationship with Letterman. Birkitt was an assistant to the talk show host and was Halderman's former live-in girlfriend.
A 27-year CBS veteran, Halderman initially had been charged with first-degree attempted grand larceny, to which he pleaded not guilty in October. He could have faced 15 years in prison if convicted of that charge.