Jockey Dean McKeown and trainer Paul Blockley were both in attendance as a British Horseracing Authority inquiry into alleged corruption began on Monday.
The pair, who deny the charges, are accused along with three owners, two former owners and two unlicensed individuals, of being involved with laying of horses to lose in 11 races between March 2004 and December 2005.
McKeown intended to represent himself at the hearing but he was accompanied by solicitor Christopher Stewart-Moore as the disciplinary panel commenced proceedings.
BHA spokesman Owen Byrne confirmed: “They were here along with five others and the inquiry is expected to last 10 days.”
Owners Clive Whiting, David Lovatt and Martyn Wakefield were all in attendance along with Whiting’s brother Vincent and former owner Marcus Reeder.
David Wright and Nicholas Rook were also among nine charged but did not appear.