Complex sentence: Rising steadily through the ranks during the Great Depression, Alderisio had become a well known strong arm man and, by the end of the decade, was working under Jake "Greasy Thumb" Guzik as a bagman delivering payoffs to judges and police officials.
Split into simpler sentences: Rising steadily through the ranks during the Great Depression, Alderisio had become a well-known strongarm man. By the end of the decade, Alderiso was working under Jake "Greasy Thumb" Guzik as a bagman delivering payoffs to judges and police officials.