Richard Allen Schoenfeld, convicted in 1976 Calif. bus kidnapping, released from prison

(CBS/AP) CHOWCHILLA, Calif. - One of three men who kidnapped a busload of California school children and buried them alive in a quarry has been released from prison after more than 35 years behind bars.

State prison officials said Thursday that Richard Allen Schoenfeld was released on parole to an undisclosed location late Wednesday. He will be monitored 24 hours a day with a GPS device.

An appeals court ordered his release earlier this year, ruling that the Board of Parole Hearings unfairly set his parole date for 2021 even though it concluded he wasn't a threat to society.

CBS San Francisco reports that Schoenfeld, his brother James, and Frederick Woods were convicted in the 1976 kidnapping of schoolchildren who attended Dairyland Union School in Chowchilla, about 35 miles northwest of Fresno, on July 15, 1976. The men left the bus behind and drove the children and bus driver, Ed Ray, to the California Rock and Gravel Quarry in Livermore. They sealed their victims in a large van that had been buried in a cave at the quarry and fitted to keep the children and driver hostage.

The kidnappers demanded a $5 million ransom for the return of the group, CBS San Francisco reports. Their captives managed to escape when the kidnappers decided to take a nap before calling in their ransom demand.