Following a month-long investigation by a Massachusetts State Police drug task force, three members of a violent Brockton drug crew were arrested and charged in connection with operating a fentanyl delivery service. One member of the drug organization remains at large.  Placido Armando Pereira, 33; Natalio Miranda, 28; and Djoy Defrancesco, 23, all of Brockton, were arrested this morning and charged with conspiracy to distribute and to possess with intent…