Devices used to deliver electric shocks to make horses run faster have been found during a raid at the stables of a Melbourne Cup-winning trainer.
Australian police found the illegal equipment – sometimes called “jiggers” – at the stables of Darren Weir.
A firearm and cocaine were also seized, and three unnamed men were arrested.
Mr Weir saddled Prince of Penzance to victory in the 2015 Melbourne Cup, when Michelle Payne became the first female jockey to win Australia’s richest race.
Local media reported that Weir was one of the three men – aged 48, 38 and 26 – but authorities refused to confirm whether 48-year-old Weir was among them.
The three men were released without charge later on Wednesday.
The raids took place at stables in Warrnambool and Ballarat and police said the three men arrested would be questioned over “sporting integrity matters”.
They include suspected offences such as obtaining financial advantage by deception, and engaging in conduct that corrupts or would corrupt a betting outcome.
The investigation leading to the raid began in August and includes allegations of bet rigging and animal cruelty offences.
“The investigation isn’t just about the use of jiggers. It goes to the heart of the offences that relate to the sporting integrity, so that’s corrupting betting outcomes,” assistant commissioner Neil Paterson told reporters.
“Today’s warrants show that Victoria Police will investigate allegations of corruption in sport and racing.”
In 2007, Victoria-based trainer Paul Preusker was banned for four years for use of an electric-shock device.
Four electric-shock devices were found at Mr Weir’s stables and Paterson said he believed footage existed of them in use.
“The allegation is that they may be used against a horse… with the aim of improving their performance on a particular race day,” Paterson added.
Racing Victoria chief executive Giles Thompson said the organisation alerted police after launching its own investigation.
“What is vital for the image of racing is that the integrity of racing is maintained,” Thompson told reporters.
“To do that, you have to investigate. We invest a huge amount of resources in our integrity team, and occasionally, you end up with issues like this.”
A veteran of Australia’s racing industry, Mr Weir holds the national record for the most wins by a trainer in a season.
The industry has previously been marred by allegations of corruption and cheating.
Last year, five trainers at a stable in Victoria were banned from the sport after they were found guilty of doping horses before races.