Left to Right: Cpl. Riordan, Engineer, Cpl. Burns, Tail Gunner, Cpl. Nepo, Radio Operator, Lt. Leighton, 2nd Pilot, Lt. Ostnes, Airplane Commander, Cpl. Beck, Armorer Gunner, Cpl. Carroll, Ball Turret Gunner, Lt. Purchase, Navigator. There were nine assigned to the crew. One of the crew is taking the picture, Unknown4. The aircraft number indicates it is a stateside photo so this photo was probably taken at Biggs Field near El Paso, Texas before leaving for Europe.
I found another picture with Leif's handwriting on the back identifying these men. Dated October 1944
Picture courtesy of Lt. Leif R. Ostnes files