Police discovered that a man allegedly killed his brother in Princeton, New Jersey, after he called 911 to report a fire and a dead body at the luxury apartment complex where the victim's body was found, prosecutors said.Matthew Hertgen, 31, is charged with first-degree murder in connection with the death of his 26-year-old brother, Joseph Hertgen. He is also charged with third- and fourth-degree weapons charges related to possession of a golf club and knife, as well as animal cruelty related to the death of a family cat.A police source who spoke anonymously to The New York Post said that