ROME—A young American on trial in Rome for the slaying of an Italian police officer has told the court that he stabbed the victim because he feared he was being strangled by a thug. Finnegan Lee Elder, 21, and a friend from California, Gabriel Natale-Hjorth, 20, are charged in the murder of a Carabinieri paramilitary officer Vice Brigadier Mario Cerciello Rega on a street near their hotel while vacationing in Rome in 2019. In the wee hours of July 26, 2019, Elder and Natale-Hjorth were confronted by a pair of plainclothes Carabinieri officers who showed up at what the Americans thought was going to be a rendezvous with the go-between in a cocaine deal gone bad a few hours earlier in a different Rome neighborhood. Cerciello Rega, 35, and his partner were assigned to respond to what prosecutors allege was a small-scale extortion attempt by the Americans after the defendants had …