© 2017, © The Author(s) 2017. Historical data on the use of force by police officers in the United States are unreliable or nonexistent. Available data, moreover, focus primarily on the behavior of patrolmen on the streets while neglecting violence by detectives during criminal investigations. Through an examination of a police torture scandal in Chicago from the early 1970s through the late 1990s, this article explains why violence during custodial interrogation often goes undocumented. In Chicago, the primary method of discovering, correcting, or preventing custodial abuse—pretrial motions to suppress statements—proved inadequate. By including the work of detectives, this article argues that a true measurement of police violence, impossible in practice, would likely be much higher than official data suggest.