By BETH HARRIS

AP Racing Writer

Medina Spirit, a 3-year-old colt whose Kentucky Derby victory in May came under scrutiny because of a positive drug test, collapsed and died after a workout Monday at Santa Anita in Southern California.

Trainer Bob Baffert said in a statment that the horse suffered a heart attack. The colt had just completed five furlongs in his second workout since finishing second in the Breeders’ Cup Classic a month ago at Del Mar.

The colt will undergo a full necropsy, as required by the racing board, to try to determine the exact cause of death.