The victim, Jason Kyle Shephard, was an avid runner from Cavalier, N.D., a small town near the Canadian border, who was studying sports marketing at a South Dakota college. He was on his second business trip to Smithson's office in Edgmont when he was killed hours after a September 2006 business dinner, authorities said.
"This person killed Jason Shephard over what? Over his desire to have sex with this young man," Thomas Lawrie, an assistant Delaware County prosecutor, said as Shephard's parents listened in the courtroom, holding a framed portrait of son.
Defense lawyer G. Guy Smith told jurors that another man supplied the drugs used at the house on the night of the crime and later lied to police about when he left Smithson's home.
"There is a dispute over who killed (Shephard), and why," Smith said. "Bill Smithson did not kill him."
Smithson, 43, of Glen Mills, faces the possibility of a death sentence, if convicted.
Smithson worked as a supervisor for Daktronics, a scoreboard manufacturer. According to prosecutors, he and friends used crystal meth and the date-rape drug GHB in relatively small amounts to enhance their sexual encounters.
Lawrie said that Smithson slipped GHB to Shephard at the house, then started taking his clothes off. Shephard apparently was conscious long enough to put up a fight and suffered defensive wounds on his arms and fingers. He was also punched in the face and then strangled with some sort of ligature, Lawrie said.
Smithson later called an ex-lover from Virginia, the prosecutor said. That man traveled to the house, encouraged Smithson to call police, and left when he refused, Lawrie said.
Smithson filed a missing person report on the absent intern, and picked Shephard's parents up at the airport when they arrived later that week. But before long, the friend in Virginia contacted authorities, and Smithson was arrested beside his grandmother's grave.
Shephard's naked body was found in his basement.
Hours before he died, Shephard had watched some adult movies in his hotel room and called several friends on the phone, as he often did late at night, Lawrie said. Smithson apparently then came and picked him up.
Along with the murder charge, Smithson is charged with kidnapping Shephard and giving him drugs, but Smith said he did neither of those things.
Shephard, who had taken a semester off from Northern State University in Aberdeen, S.D., to work at Daktronics, met Smithson when Shephard visited the Pennsylvania office a month earlier on a business trip. Smith described their relationship as "friendly."
"Was it more than friendly? You'll have to decide," Smith told jurors.