A leading Irish vet has been cleared of passing on inside information before top hurdler Faugheen's withdrawal from the 2016 Cheltenham Festival.
Tim Brennan, who was alleged to have conspired with his brother Michael, was charged by the British Horseracing Authority (BHA).
Michael is alleged to have placed 'lay bets' against the horse for the Champion Hurdle at Cheltenham.
But Tim Brennan was cleared by a BHA disciplinary panel of any wrongdoing.
The BHA stressed at the time the charges were announced that Faugheen's trainer Willie Mullins was not involved in any alleged wrongdoing.
The horse, nicknamed 'The Machine', won the Champion Hurdle in March 2015 but was ruled out of a title defence the following February with a leg injury.
The BHA claimed that Tim Brennan, who denied the charges, had passed on information to the prospects of Faugheen which was not publicly available, having obtained the information in his capacity as a veterinary surgeon to the horse.
But after considering all the evidence before it, the disciplinary panel concluded that it "has not been proved to the appropriate standard that Timothy Brennan was the source of any confidential information to his brother".
Michael Brennan refused to cooperate with the BHA's investigation and was excluded from the sport in October 2016, meaning he is barred from entering racecourses or racing stables.
The panel ruled that, in its view, Tim Brennan "at the material time in all the circumstances placed before the panel" was not subject to the Rules of Racing, as a self-employed veterinary surgeon.
Delivering its verdict, the panel added: "So far as is known, this issue has not been canvassed before, and on balance the panel preferred the submissions made on behalf of Timothy Brennan to those made on behalf of the BHA.
"The panel concluded that there were, on the evidence, a number of other realistic possibilities for the source of any such information.
"The panel considered that Timothy Brennan had cooperated throughout the investigation. The panel had the advantage of seeing and hearing Timothy Brennan give evidence and be cross-examined for the best part of half-- day and found him to be a credible witness who did not seek to avoid any of the matters put to him.
"Notwithstanding their findings, the panel consider that the BHA on the information available at the time were acting reasonably in instigating an enquiry in respect of Timothy Brennan."
The BHA said in a statement: "Had we had cooperation from the key witness in the case, Timothy Brennan's brother, this matter might have been resolved much sooner. Notwithstanding, it was important to set the evidence in front of an independent panel.
"We await the independent panel's full written findings before we can comment further on the detail of this case, including the issue of jurisdiction which the panel examined."
Tim Naylor, the BHA's head of regulation, said: "Mr Brennan was subject to a fair hearing in front of an independent disciplinary panel.
"There was evidence which required examination, as the panel has recognised, and we note their finding that the BHA acted reasonably.
"We will continue to charge potential breaches of the Rules of Racing in order to protect the integrity of our sport."
BBC horse racing correspondent Cornelius Lysaght
Although the panel concludes the British Horseracing Authority was 'acting reasonably' here, the result is no surprise.
Evidence presented often seemed circumstantial, and ultimately a system renowned for taking its time has delivered a not guilty verdict in barely 48 hours.
The Authority is seemingly a lot better at politics - like sorting out funding, for example - than regulation.
Other cases, including a very serious doping allegation against trainer Hughie Morrison last year, have failed, and, on a more day-to-day basis, matters are poorly handled and/or communicated, and its attitude towards some relatively minor disciplinary matters often looks heavy-handed.