NAHANT – Jeffrey Chelgren was officially sworn in Monday morning at Nahant Town Hall, becoming the town’s fourth town administrator.”Mark (Cullinan, previous town administrator) set a very high bar for me,” Chelgren said Monday. “What I have to do is learn the processes and the priorities he set forth, get to know the boards and committees and citizens and learn what some of the issues are.”Chelgren was most recently town administrator in Marblehead, but was familiar to Nahant selectmen and citizens, having been a finalist for Cullinan’s position in December 2011.Selectmen chose former Saugus Town Manager Andrew Bisignani, who lives in Nahant, instead. Bisignani resigned, however, in June – a mutual decision made along with selectmen.State Police detectives raided Nahant Town Hall days later, and Bisignani has pleaded not guilty to charges including procurement fraud, tampering with public records and misleading persons related to a grand jury summons by altering public records. He is charged with eight counts of criminal activity relating to his tenure in Nahant; and four counts relating to his tenure in Saugus.Cullinan returned to his former position – which he had held since 1995 – in an interim role.Chelgren meanwhile had been hired as town administrator in Marblehead, but resigned in January.Chelgren was offered the Nahant role after Sean Fitzgerald, former town administrator in Plaistow, N.H., declined the offer in Nahant to accept a position in Saugus. Fitzgerald’s contract was subsequently voided after four of the town’s five selectmen were recalled.But Selectman Richard Lombard and Board of Selectmen Chairman Perry Barrasso said they were both very happy to see Chelgren sworn into office Monday.”I got my first choice,” Barrasso said. “I think he’s the right man personally, professionally and across the board.”Lombard agreed.”He said he’d like to retire from here after the next 15 years; and we liked that,” Lombard said.Chelgren said he was very excited to be at the helm in Nahant, and expected to get right to his work, as Town Meeting is April 25.