The female, African-American sprint car driver had Indy 500 ambitions, but why did the promising racer’s dream turn to tragedy? — By Marshall Pruett The coroner listed her cause of death as drowning. Detectives from the Seattle police department ruled her death a suicide, the result of jumping off the Aurora Bridge into Lake Union. Her family disputes any notion she chose to go over the edge, willfully plummeting 167 feet…