What's to blame for the death of Dan Wheldon?

INDIANAPOLIS - IndyCar has launched its probe into the crash in which Dan Wheldon died, and hopes to have a preliminary report within weeks, the US open-wheel racing series said in a statement on Wednesday.

Wheldon, a 33-year-old English driver who won the famed Indianapolis 500 twice, died on Sunday when he was caught up in a stunning chain-reaction crash at Las Vegas Motor Speedway in what would have been IndyCar's season finale.

Fifteen cars were involved in the fiery melee on the 12th lap, after which the race was cancelled.