The passenger's identity is unknown. Stephan told his girlfriend he was giving a man a ride toward Keys, and witnesses had previously seen an unfamiliar man on campus asking for transportation to that area. The Oklahoma State Bureau of Investigation released a composite sketch of an unidentified man, but the lead yielded no breakthrough.
He was last seen between 11:30 a.m. and noon at a convenience store in the Cookson area near Lake Tenkiller. Witnesses noted he appeared anxious and was alone before he drove out of the parking lot heading northbound.
Stephan left behind cash, untouched bank accounts, and the prescription asthma inhalers he never left home without. Furthermore, his cell phone never made another outgoing transmission after the morning he vanished, and his truck was never recovered.
Stephan was involved in a contentious legal battle with his ex-wife and had a critical court hearing scheduled just eight days after he disappeared. Family members reported that hostile threats had been made against him, including rumors that an individual vowed he would never make it to that court date.
The grand jury formally determined that Stephan was the victim of a homicide. The panel also stated that his killers were very likely among the individuals who testified before them under oath.