Complex sentence: Attardi's efforts would allow Tremoglie to infiltrate the New York Mafia's drug trade and, assisting in police surveillance, helped ensure the success of the sting operation and, upon collecting $5,000 for his assistance, Attardi quickly left the country with his girlfriend.
Split into simpler sentences: Attardi's efforts would allow Tremoglie to infiltrate the New York Mafia's drug trade and, assisting in police surveillance, helped ensure the success of the sting operation. Upon collecting $5,000 for his assistance, Attardi quickly left the country with his girlfriend.