Authorities have identified the man found dead in a house fire in Trenton early Sunday as a 57-year-old who was “staying at the residence.” Brian Wharton, of Trenton, was already deceased when firefighters entered the home on the first block Summer Avenue shortly after midnight, the Mercer County Prosecutor’s Office said Monday. Prosecutors said Whaton was discovered on the first floor. Flames were shooting from windows on both floors when firefighters arrived. Summer Street is a narrow, one-way street off Calhoun Street, on the boundary of the West and North wards. The cause and origin of the…