Semenya's future still clouded by gender dispute

South Africa's Caster Semenya is back and vowing to win an Olympic gold medal that could reignite the complex biological and ethical gender storm that once engulfed her life.

The runner, who was at the center of a bitter dispute over gender testing seven years ago, is favored to win the women's 800 meters in Rio next month.

Semenya shot to international stardom in 2009 when she won the 800 at the World Championships in Berlin, but her victory triggered a storm of controversy when rivals questioned her gender.