Eight years after the killing of a congressman triggered the mass murder-suicide of the Peoples Temple cult in a South American jungle, the second trial of former temple member Larry Layton was sent to a San Francisco federal court jury. Layton, 40, the only former disciple of the Rev. Jim Jones to be tried in the United States in connection with the events, is charged with conspiracy and aiding and abetting in two shootings--the killing of California Rep. Leo Ryan and the wounding of Richard Dwyer, deputy chief of the U.S. mission in Guyana. Layton's first trial, in 1981, ended in a hung jury. He is free on bail and has been working in a local community under an alias.