GREELEY, Colo. -- A Weld County liquor store owner will not be charged after fatally shooting a robber who was holding a pistol-grip water nozzle, the district attorney announced Monday.

Police said that Douglas Wies, 32, of Fort Collins, Colo., was shot in the head and killed during a robbery attempt on July 8 at the Corner Liquor Store in Windsor, Colo.

An investigation of the shooting determined that the liquor store owner, Ron Trauernicht, 59, shot Wies because he thought Wies was going to shoot Norma Trauernicht, Ron's wife.

The robbery attempt began when police said that Wies entered the store and said he had a gun. He had something in his hand covered by cloth and used it to order store employees and two customers into a back cooler.

Police said that Wies was taking money from the cash register when Norma Trauernicht came out of the cooler and confronted him. Wies pushed her to the floor as Ron Trauernicht came out of the cooler and grabbed a .357-caliber revolver he kept in the store for protection.

Ron Trauernicht told Wies to put his weapon down, but told investigators that Wies pointed the simulated weapon at Norma Trauernicht's head. That's when her husband fired a single shot at Wies, striking him in the forehead. He died four days later.

Police found Wies was not armed with a weapon but with the water sprinkler covered with cloth to simulate a gun.

Weld County District Attorney Kenneth R. Buck determined that Ron Trauernicht acted within the law because he believed that he and his wife were in imminent danger of being killed and that he believed a crime was being committed when he fired the fatal shot.

An investigation revealed that Wies was suspected in at least four robberies in Greeley and Loveland. In all of the robberies, police said he covered his hand to make it appear he had a gun.