Bruce T. Marston enlisted in the Army Air Corps as an Aviation Cadet on September 30, 1941. According to the enlistment record on the National Archives and Records Administration website, he was born in California in 1916, was a resident of Los Angeles County, had completed two years of college, and was employed as a salesman.
Major Marston flew with the 501st Bomb Squadron, 345th Bomb Group from the earliest missions in June 1943. By the end of November that year, he began flying with all four of the squadrons.
I found flight data that lists him as pilot on thirty-two missions, from June 1943 through June 1944.
Major Marston became the Group Operations Officer for the 345th at some point during his time in New Guinea.