The Clackamas County District Attorney will not prosecute Brian Schaffer, 53, because a police investigation found Schaffer thought he hit a deer about 7 p.m. March 2 and couldn't find what he struck after searching the dark, unlit area during heavy rain, the sheriff's office said. An investigation also found evidence that Katherine Rusk, the woman hit by Schaffer's Ford F-150, drank alcohol before the crash and was seen walking in the street, according to the sheriff's office.