CLEVELAND — An Ohio man was sentenced to 15 years in federal prison for selling cocaine laced with heroin and fentanyl to a Greek billionaire’s son who was found dead in a Cleveland hotel room.

Terry Lee Christian, 36, pleaded guilty in October to charges related to selling the drugs that killed 34-year-old Sokratis S. Kokkalis in July 2018 and for using a cellphone in a drug transaction. He was sentenced Wednesday in federal court in Cleveland.

Christian sold the drugs to Kokkalis outside Jack Cleveland Casino, authorities said. Christian said at his plea hearing that he thought the drugs contained only cocaine. Kokkalis was in Cleveland for a gambling conference.

Kokkalis’ father, Socrates P. Kokkalis, is the founder of a Greek telecommunications company and chairman of the Greek soccer team Olympiacos F.C. His son was the team’s vice president.

A message seeking comment was left Thursday with Christian’s federal public defender.