Britain's Prince Harry, the youngest son of Princess Diana, has said in a television interview that "no one will ever know" what happened in the Paris car crash that killed his mother 10 years ago this August, according to dpa. "I'll never stop wondering about that," Harry, 22, said in a joint interview recorded for US television with his brother William, aged 24, in which both princes spoke unusually openly about their mother's death. "I don't know for...for me personally whatever happened that night. Whatever happened in that tunnel. You know no one will ever know," Harry said in the NBC interview, extracts of which were reported by Britain's Press Association Tuesday. The full interview is scheduled to be broadcast by NBC news next Monday.