A former Manchester police officer accused of assaulting a man he was trying to arrest is set to go on trial today. Scott Knutson is charged with assault causing bodily injury for an incident last June. Knutson allegedly slammed the head of a 19-year old man against a car. The man suffered neck and other injuries. Knutson says the man was trying to hide evidence and flee the scene after being stopped on alcohol violations. Knutson was indicted by a Delaware County grand jury, but the trial has been moved to Buchanan County on a change of venue.