BOLINGBROOK, Ill. (AP) -- Former Bolingbrook police officer Drew Peterson is expected to be released from jail later today after turning himself in to authorities on a weapons charge.

Peterson attorney Joel Brodsky says Peterson's adult son posted $7,500 bail and that Peterson was being processed.

Brodsky says the charge involves a gun seized after Stacy Peterson disappeared in October. Peterson has been named a suspect in his wife's disappearance.

Brodsky says police claim the gun's barrel was too short under Illinois law.

The attorney says the weapon is an AR-15 semiautomatic assault rifle that Peterson used while he was a police officer. He contends police officers are exempt from the length provision of the law and Peterson was still a police officer when the gun was seized.