From the BHA website: emphasis is mine
After considering the evidence, including written statements from Mahmood Al Zarooni, the Panel was unable to establish the source of the substance, and COULD NOT THEREFORE BE SATISFIED THAT THE ADMINISTRATION OF THE SUBSTANCE WAS ACCIDENTAL.
The Panel accepted an admission from Mahmood Al Zarooni that he was in breach of Rule (C)53 on both occasions and imposed a fine of £1,000 for each breach.
Guilty until proven innocent: what a change from the Magna Carter.