CHICAGO --Chicago police superintendent Jody Weis is changing the way bank robberies are investigated in Chicago.Detectives assigned to a joint task force with the FBI will continue to work on the cases. But other detectives will not. Department leaders say that will free them up to investigate murders and other crimes. "Their time is better spent handling the street robberies that occur every day in the neighborhoods out here as opposed to a bank robbery which is already being handled by another squad," said Dep. Supt. Steve Peterson, Chicago Police Department. Police union leaders says the idea is not without merit. But they're unhappy because the change wasn't fully explained to officers before it went into effect. The joint task force has operated for 18 years and was created in part to help relieve duplication.