Boone was last seen at approximately 3:00 p.m. on December 5, 2006 at his residence in the vicinity of the 26300 block of Town Center Drive in Foothills Ranch, California. He has never been heard from again. His teenage son reported him missing early the next morning when he did not come home.

Bloodhounds subsequently tracked Boone's scent from his apartment to the Whiting Ranch Wilderness Park nearby. The park is a popular place for hiking and bike riding. Authorities believe Boone went hiking there on the day of his disappearance. An extensive search of the park turned up no sign of him, however. The search was called off after one week. Investigators believe that if Boone did in fact get lost or injured while hiking, he could not have survived long in the cold winter weather.

Boone did not take his credit cards, identification, money, vehicle or cellular phone with him when he went missing, and his adult children and his ex-wife stated it was uncharacteristic of him to leave his youngest son home alone for days. He was going through a divorce in December 2006 and may have been stressed because of that. At the time he went missing, Boone was employed as a golf club designer; he has designed clubs for many professional golfers. His case remains unsolved.