An American schoolteacher has been murdered in a remote village of eastern Colombia, a spokesman for her U.S. institute said. Joan Marie Roroff Albel, 37, was stabbed in the heart last Sunday in Lomalinda, in a jungle province where the Summer Institute of Linguistics has its headquarters. The killer, described as mentally deranged, was arrested. The institute became prominent in 1981 when one of its translators, Chester Bitterman, was kidnaped and murdered by leftist guerrillas. The institute, which translates the Bible into tribal dialects, has been accused of interfering with Indians’ traditions.