(Portland, OR)  --  The Portland Police Bureau is trying out a new tactic in its investigations of shootings.  Officers normally canvass nearby homes looking for information, and if no one is home, they plan to start leaving door hangers to let residents know they're investigating a shooting.  The door hangers will list the time of the shooting and who to contact if they have information.  Police say witness information is the only way they can solve many of the gun crimes.  Police are asking for public input on the design of the door hangers before they start using them.