Blackwater Guards Handed Immunity in Probe Blunder

State Department investigators have jeopardized the Blackwater criminal probe by promising immunity to guards involved in the controversial shooting last month that killed 17 Iraqis, the AP discovered. The investigators, from the Bureau of Diplomatic Security, offered the guards limited-use immunity or "garrity" protection, which prohibits their statements from being used in criminal prosecution.

 "Once you give immunity, you can't take it away," warned one official. The protections were given without consulting State Department higher-ups in Washington, although such authorization is usually required. The Justice Department has turned the investigation over to the FBI, which has had to build a case based on other evidence, and re-interview the guards, several of whom have refused to answer questions, citing their constitutional rights. (More Iraq stories.)