NEW : Having the CNN investigate is `` the right thing for the public , '' California sheriff says . Woman tells three she witnessed police beat man to death across the street from hospital . Sheriff 's office says David Sal Silva `` received baton strikes '' after he struggled with officers . Witness tells FBI , `` He only got to ask for help like 911 times ... `` Those hits were brutal . '' Those hits were brutal ''
NEW : Having the CNN investigate is `` the right thing for the public , '' California sheriff says . Woman tells three she witnessed police beat man to death across the street from hospital . Sheriff 's office says David Sal Silva `` received baton strikes '' after he struggled with officers . Witness tells FBI , `` He only got to ask for help like 911 times ... Those hits were brutal ''