BOZEMAN, Mont. -

 A former Gallatin County sheriff's deputy has pleaded no contest to misdemeanor assault after prosecutors say he grabbed a shackled teenage runaway by the throat and threw her against the wall of an interview room. 

Thomas Madsen was initially charged with felony mistreatment of a prisoner for the March 2011 confrontation.
    
Last week, District Judge Holly Brown ruled the state could not use its video evidence because it had not preserved all of the video related to the encounter.
    
The Bozeman Daily Chronicle reports Madsen entered his plea to the misdemeanor charge Thursday. He was originally charged with felony mistreatment of a prisoner.
    
Brown's sentence for Madsen was deferred through Aug. 31. If he remains law abiding, the charge will be dismissed.