DENVER (AP) _ Police have changed their policy on so-called no-knock search warrants because one man was killed in an apparently unfounded raid.

Ismael Mena, 45, was shot eight times by Denver SWAT officers during a Sept. 29 raid. Officers said they found Mena in a shooting stance, pointing a gun at officers and refusing to lower it.

Mena's son, Heriberto Mena, said his father's friends and neighbors think he may have thought he was protecting himself against an intruder.

Police and Denver district attorney's office are investigating.

Under the new policy, a police supervisor must now approve all requests for search warrants written by street officers.

It was instituted Nov. 10 as a result of the Mena case, said a police spokesman, Sgt. Tony Lombard.

The warrant for Mena's house was requested by an officer who said he saw ``a previously reliable confidential informant'' go to the house, where the informant said he or she bought crack.

No drugs were found in the home and an autopsy showed no drugs in Mena's system, authorities said.