Islamic extremists may have murdered four members of a Coptic Orthodox family found bound, gagged and with their throats slit on Friday in their Jersey City home, a law-enforcement official familiar with the case said. The official confirmed that Hudson County investigators, as well the FBI, were "knee-deep" in pulling computer records and were coming to terms with the possibility that the family may have been targeted for death because of exchanges about religion in an Internet chat room. The official cautioned, though, that investigators have not ruled out other possibilities, such as a robbery gone awry. Hossam Armanious, 47,...