Three days after General Augusto Pinochet returned home after his house arrest in Britain, a judge asked a Chilean court to strip the former dictator of his congressional immunity so he could stand trial. Yesterday’s request by Judge Juan Guzmán was a step toward putting Pinochet on trial for the killing and disappearance of 72 dissidents in the days following his 1973 coup. Guzmán has already indicted several other military officers including two generals in the same case. The 22-member Santiago Court of Appeals would be the first to rule on Pinochet’s immunity, after which either side can appeal to the Supreme Court. The process may take weeks, even months. Some have expressed concern that the military, which still strongly supports their former leader, may apply pressure to abort any trial.