Complex sentence: Abbandando later became a hitman for Murder, Inc. During the 1920's and 30's, Abbandando was reputed to have killed thirty people, mostly in Brooklyn.
Split into simpler sentences: Abbandando later became a hitman for the Murder, Inc. organization. During his time as a Murder, Inc. hitman in the 1920's and 30's, Abbandando was reputed to have killed thirty people, mostly in Brooklyn.