Middlesex County People Holding Office Name: Barry Kelleher Offices Held: Sheriff Party: Democrat From: Wilmington, Mass Name: Michael Sullivan Offices Held: District Attorney Party: Democrat Name: Marian Ryan Offices Held: District Attorney Party: Democrat Name: Ernest Petrone Offices Held: Sheriff Party: Unenrolled Name: Brian Gillis Offices Held: Sheriff Party: Democrat Name: Robert DeMoura Offices Held: Sheriff Party: Democrat Name: Tara DeCristofaro Offices Held: Register of Probate Party: Democrat Name: John Buonomo Offices Held: Register of Probate Party: Democrat Name: James DiPaola Offices Held: Sheriff Party: Democrat Name: Peter Koutoujian Party: Democrat