When the authorities finally caught up with Kuklinski in 1986, they based their case almost entirely on the testimony of an undercover agent. New Jersey State Police detective Pat Kane started the case 6 years prior to the arrest and the investigation involved a joint operation with the New Jersey Attorney General's office and the Bureau of Alcohol, Tobacco and Firearms.
Special Agent Dominick Polifrone had undercover experience specializing in Mafia cases. The New Jersey State Police and the Bureau began a joint operation. Detective Kane recruited Phil Solimene, a close friend of Kuklinski, who introduced undercover agent Polifrone to the killer.
The Bureau agent had acted like he wanted to hire Kuklinski for a hit and recorded him speaking in detail about how he would do it. When state police and federal agents went to arrest Kuklinski they blocked off his street, and it took multiple officers to bring him down.
In the process of doing so Mrs. Kuklinski was also arrested and charged with gun possession because the car was in fact registered under her name. When Mrs. Kuklinski was arrested a police officer put his boot on her back while detaining her. This enraged Kuklinski and that is one the reasons why they needed multiple officers to bring him down.