why doesn't the US Justice Department do somehting to clean up the police in this country?

Kennett Square PA cop sentenced to 12.5-25yrs prison in plea deal for raping 4 young girls for several years [0] http://bit.ly/GTFc79

Rockaway Beach OR cop gets probation in reduced charge plea deal for soliciting nude pics from 14yr-old student [0] http://bit.ly/GRXfFk