Altmann is an Austrian national. He traveled to Los Angeles, California in October 1984 to invest in real estate. Altmann checked into the Regent Beverly Wilshire Hotel in Beverly Hills, California on October 26. He told the hotel officials he planned to check out on October 31. He was due to return to Austria on November 2.

Altmann was last seen in his hotel room on October 30. He is believed to have gone sightseeing in the Big Sur area that day. He was driving a white 1984 Chevrolet Camaro, with California license plates numbered 1JDK196. The car, which he rented from Budget Rent-a-Car, has not been recovered.

Altmann's wife reported him as a missing person on November 6, 1984, a week after he was last seen. Hotel workers checked his room at this time and found his passport, clothing, money, and return plane ticket undisturbed. Altmann has never been heard from again. He is believed to be missing under suspicious circumstances.