Dietrich Helmut Jonke, 68, was last seen June 8, 1983, after leaving Los Angeles on a flight to Berlin with a layover in London. Flight records confirm he arrived in London but he never boarded the connecting flight to Berlin and has not been seen or heard from since. At the time he was 5 feet 6 inches, 118 pounds, with gray hair and brown eyes; dental records are available to investigators.

The Los Angeles Police Department classifies the case as an endangered missing person investigation. Few details have emerged about his movements after arriving in London, and the international routing complicates efforts to trace him. There has been no confirmed sighting or new evidence since June 1983.

If anyone has memories of seeing Jonke in June 1983 or information about his time in London that day, please contact the Los Angeles Police Department.