All police in Ocampo arrested in internal affairs 'code of conduct' investigation

Fernando Angeles Juarez, 64, was gunned down outside his home on Thursday

Police stopped federal agents from arresting murder suspect in armed standoff

Reinforcements made the arrest the next day and rounded up all the officers

Mr Juarez is the third candidate in his state to be murdered in 10 days

More than 120 candidates killed ahead of the July 1 elections, the most ever