The kingpin started in bowling — the front pin whose fall brings down the rest — perfectly describing why law enforcement targets the leader to topple a criminal organization.
The most important person in a group or enterprise, especially a criminal organization; originally, the front or central pin in bowling.
A compound of king (from Old English cyning, ruler) + pin (from Old English pinn, a peg or bolt). Originally the most important pin in ninepins or tenpins bowling — the front or center pin whose fall determines the others. The figurative sense of a leader or most important person developed from this. Key
The kingpin was originally just a bowling term — the front pin in ninepins, whose removal made all the others easier to knock down. This perfectly describes how law enforcement targets criminal kingpins: remove the central figure and the organization collapses. In automotive engineering, the kingpin is the bolt around which the front wheels pivot for steering