Born Domenico Brucceleri, Brooklier joined Mickey Cohen's syndicate gambling operations in Southern California in the 1940s under the name Jimmy Regace. During the Sunset Wars of the 1940s, Brooklier defected to rival Los Angeles mobster Jack Dragna's Los Angeles crime family. In 1947, Brooklier he became a made man in the family. While working for Dragna, Brooklier unsuccessfully attempted to assassinate Cohen as he left a restaurant. From 1947 to 1953, Brooklier worked closely with Los Angeles family member Jimmy Fratianno in loan sharking. At some time in the late 1960s, Brooklier was promoted to caporegime in charge of a crew in Orange County, where he also lived. Sometime later, he legally changed his name to Dominic Brooklier.