Kalaf was last seen on July 24, 1996 as he traveled from Tucson, Arizona to a drilling job site located between Tombstone and Gleason, Arizona. He was supposed to stay at the Adobe Lodge motel in Tombstone. He never arrived at his destination and has never been heard from again.

Kalaf's 1989 silver Dodge Ram pickup truck was discovered abandoned in October 1996, three months after he was last seen. The vehicle was stuck in a ravine in a rugged, mountainous area approximately 17 miles from Kalaf's drilling job site. Kalaf's personal belongings and uncashed employee paychecks were found inside the vehicle. Authorities found plastic flagging tape extending northeast from the vehicle and believe Kalaf was trying to mark his direction of travel. He apparently went east towards the Dragoon Mountains, rather than left towards civilization. Eventually the flagging tape stopped appearing, and Kalaf was never located in spite of an extensive search.

Kalaf is described as being well-educated. His case remains unsolved.