FBI Investigating Missouri Officer's Use of Stun Gun on Teen

The FBI said Monday it had launched an investigation into an incident that left a 17-year-old hospitalized after he was subdued by an Independence, Mo., police officer with a stun gun.

Independence police said that they would cooperate "hand-in-hand" with the federal investigation and the officer had been placed on administrative leave.

Those developments came as witnesses to the Sunday afternoon traffic stop of Bryce Masters of Kansas City said they thought the officer had treated him more roughly than necessary. They also said the incident was complicated by what appeared to have been a malfunctioning car window and the officer's frustration at the teen for not lowering the window, the Kansas City Star  reports.

Masters was in critical condition Monday in a hospital intensive care unit. The officer, identified by the Independence department as Tim Runnels, has been on the force nearly three years.