One co-operated with the investigation of an injection given by a vet in his own stable and seems to have effectively pleaded guilty before the eventual enquiry is held.
The other administered an injection himself in the racecourse stables, then denied all knowledge of it, eventually changing his story to the effect that he had given an injection, but it was a different substance and that he’d done it in the horsebox, not in the stables. Even after he was found guilty, he still refused to accept he’d done anything wrong and appealed the decision.