Police have arrested two people today for their alleged role in the killing of two engineers of a private road building company who were shot dead in Bihar's Darbhanga district last month. Munni Devi, head of Baheri block and also sister of gangster Santosh Jha, and her husband Sanjay Laldeo were arrested from outside Laheriasarai station, Deputy Superintendent of Police Anjani Kumar Singh said.