Trainer Mahmood Al Zarooni on Thursday arrived for a disciplinary hearing at British racing's governing body over doping allegations that have rocked the sport.
The 37-year-old was met by a crowd of photographers and television cameras outside the British Horseracing Authority's offices in central London but said nothing to waiting reporters.
The BHA charged Al Zarooni on Wednesday with breaching rules "related to prohibited substances, duty to keep medication records, and conduct prejudicial to racing".
The charges relate to samples taken earlier this year from 45 horses at the Newmarket, eastern England, yard owned by the leading Godolphin outfit.
Analysis of the samples revealed that 11 contained traces of the banned anabolic steroids ethylestranol and stanozolol.
Godolphin owner Sheikh Mohammed bin Rashid Al Maktoum reacted to what has been described as racing's biggest doping scandal in recent years by shutting the stables and ordering a full-scale internal investigation.
The sheikh, one of racing's leading figures and the ruler of Dubai, said he was "appalled and angered" by the revelations.
Al Zarooni has said the situation was a "catastrophic error" and claimed that he did not realise he was in breach of racing rules by administering the drugs.
The BHA said on Wednesday that he had told investigators that a further four horses that were not tested were also given the banned substances.