SAN FRANCISCO (AP) — A California prosecutor said Monday he has filed murder charges that could lead to the death penalty for three young transients accused of gunning down a Canadian backpacker and a yoga instructor walking his dog. The three were arrested last week in Oregon. They are expected to be booked in Marin County jail Monday. Marin County District Attorney Ed Berberian said each suspect is charged with two counts of murder with special circumstances, including lying in wait.