The Age and the Sydney Morning Herald can reveal that Racing Victoria is preparing to charge McLean with possessing the banned substance Erythropoietin, commonly known as EPO, and administering the drug to Cats Fun, a horse which last raced in 2014 and has since died.

McLean and Weir are separately facing multiple counts of animal cruelty and other criminal charges relating to their alleged use of a jigger, a cattle prod-like device which administers an electric shock, to Weir's 2018 Melbourne Cup runner Red Cardinal and two other horses.

EPO, a substance which boosts the amount of oxygen that can be absorbed by blood, was used by cyclist Lance Armstrong to cheat his way to victory in the Tour de France. When administered to a race horse, it can enhance aerobic capacity and staying power.

McLean attempted to scupper the doping case against him by challenging in the Victorian Supreme Court the legality of Victoria Police sharing with Racing Victoria material obtained under a criminal warrant.

Justice Melinda Richards today dismissed his application for a permanent injunction to prevent Racing Victoria relying on any information about the seized syringe and its contents.

The decision clears the way for Victoria Racing to pursue McLean and for The Age and the Sydney Morning Herald to reveal the doping case against him. In a late night court hearing earlier this week, McLean's lawyers obtained temporary orders preventing the mastheads from reporting his alleged use of EPO until Justice Richards handed down her judgment.

Court documents lodged by McLean and Racing Victoria outline a complex doping case which would have likely remained buried if not for Victoria Police's chance discovery of the discarded syringe earlier this year at McLean's Yangery property near Warrnambool.

Police found the syringe on January 30, the same day they executed search warrants at Weir's Warrnambool training centre, where McLean was employed as stable foreman, and at Weir's home stables at Miners Rest, near Ballarat.

Police separately found three jiggers in the master bedroom at the Miners Rest property.

Weir, a leading trainer in Australian racing, was banned for four years by the Racing Appeals and Disciplinary Board after pleading no contest to possessing the jiggers and conduct prejudicial to racing.

Police sent the syringe for testing at Racing Analytical Services, a lab used by racing authorities to test swabs taken from horses. A certificate of analysis provided by Paul Zahra, the lab's scientific manager, revealed the presence of EPO.

From there, Victoria Police sought the help of Dr Natasha Hamilton, the director of the Equine Genetics Research Centre in Scone, NSW. On 15 August, she provided police with a report linking traces of blood left in the syringe to a gelding named Cats Fun.

Cats Fun was trained by McLeod between 2009 and 2013 before shifting to Weir in 2014, then back to McLean for the last two races of his career. He recorded five wins from 45 starts including a home-town victory for McLean in the 2013 Brierly, a gruelling, 3450m steeplechase event worth $100,000 run as part of the Warrnambool carnival.

Police provided Mr Zahra's analysis and Dr Hamilton's report and other material to Racing Victoria head of integrity Jamie Stier on 23 August and a week later, McLean was formally interviewed by racing authorities.

The 38-year-old trainer was told before the interview that stewards intended to charge him with possession and administration of a prohibited substance.

Racing Victoria has adjourned the anti-doping proceedings against McLean until the Supreme Court case is resolved. McLean has accused Victoria Police of acting unlawfully, contravening its statutory duties and breaching Victoria's Charter of Human Rights and Responsibilities by sharing confidential information with Racing Victoria.

McLean did not respond to questions from The Age.

The start to Victoria's spring racing carnival has been overshadowed by the developing scandal implicating Weir, McLean, stablehand Tyson Kermond and retired jockey William Hernan.

The most damaging allegation so far is that Weir, a nationally acclaimed trainer who won 3677 races in the past decade including the 2015 Melbourne Cup involving Michelle Payne and amassed $148 million in prize money for his owners, authorised the use of a jigger to torment his runner in last year's Melbourne Cup, Red Cardinal, days before the race.

The Age last week revealed that Victoria Police recorded the distressing scene with a camera hidden inside Weir's Warrnambool stables. Kermond is allegedly shown applying the jigger to the horse's neck while McLean and Weir watch on.

Victoria Police announced last week that they had charged Weir, McLean and Kermond over the criminal mistreatment of animals and conspiring to defraud racing stewards. Hernan was charged for placing a bet on a horse that had been jiggered before a race.

The doping case against McLean, who was last week suspended indefinitely from training, does not relate to the criminal charges against him. Weir, McLean, Kermond and Herman are listed to appear before the Melbourne Magistrates Court for a filing hearing on 23 October.

Have you signed up to the Bendigo Advertiser's daily newsletter and breaking news emails? You can register below and make sure you are up to date with everything that's happening in central Victoria.