A New Jersey State Police trooper died Sunday during training at the agency’s headquarters in Ewing, officials said. Trooper Marcellus E. Bethea, assigned to the Moorestown Station in Burlington County, was a trooper for over eight years, the agency announced on X (formerly Twitter). State Police officials did not give any details about what training Bethea was undergoing, how he died or the tie of the incident. An investigation of Bethea’s death was ongoing Sunday night, officials said. Gov. Phil Murphy and his wife, Tammy, mourned and lauded Bethea in a statement, saying: “Trooper Bethea sho…