Prosecutors have finished an investigation into five former police officers suspected of negligence in a case where a young man Prosecutors have finished an investigation into five former police officers suspected of negligence in a case where a young man choked to death after being taken into custody.

The Beijing People's Procuratorate referred the case to the public prosecution on Tuesday.

Four of the suspects have been released on bail. A fifth, surnamed Xing, former deputy director of Dongxiaokou police station in Changping district, is still in custody, the procuratorate said on Tuesday.

Lei Yang, 29, choked to death on his vomit shortly after being taken into police custody, according to an independent autopsy released on June 30.

He was detained on suspicion of soliciting prostitution on May 7, but refused to cooperate and was handcuffed after attempting to escape. He was taken to hospital and pronounced dead hours later, according to previous police statements.

At least one of the suspects was an auxiliary officer.

On Tuesday, the State Council, China's Cabinet, released a regulation targeting management of auxiliary officers, requiring a thorough investigation and cleanup across the country.

Auxiliary officers are necessary for public security, but there are some problems in how they are managed, the State Council said.

The regulation stipulates specific management rules, including listing their responsibilities, recruitment requirements and supervision, aiming to straighten out management and improve services by the end of next year.

Public security authorities are required to conduct thorough investigations on auxiliary officers, it said.