A San Francisco man who wandered across the frozen Bering Strait into Russian territory April 2 was returned to American soil by Soviet helicopter--and was sent home after interviews with federal agents and a psychiatric social worker. Jon Weymouth, 33, of San Francisco, was arrested by the Soviets April 9--a week after he crossed the three miles from Little Diomede Island to Big Diomede Island. Alaska State Trooper Capt. Joe DeTemple said Weymouth “was reasonably calm, just a little depressed” after the Soviet helicopter delivered him to a village public safety officer on Little Diomede, in American territory. DeTemple said Weymouth remained in Nome overnight before being flown to Anchorage, where he was to board a flight for California.