Authorities say 19-year-old William Mack Sapp of south St. Louis County is charged with second-degree assault and leaving the scene of an accident. He is jailed on $500,000 bond following his arrest on Wednesday. It wasn't immediately clear if Sapp had an attorney.
The other alleged racer, 19-year-old Trenton Pinckard of Glen Carbon, Ill., was charged earlier this week with leaving the scene of an accident.