Disqualified trainer Darren Weir has been charged by police with defrauding racing officials and animal cruelty, after jiggers were seized during January property raids.
Detectives from the Sporting Integrity Intelligence Unit charged four men on Wednesday.
The 49-year-old Weir, who now lives in Baringhup near Maldon, has been charged with nine offences.
Charges against the former trainer include conspiracy to defraud Racing Victoria stewards, three counts of engaging in torturing, abusing, overworking a thoroughbred race horse, three counts of causing unreasonable pain or suffering to a race horse, possessing an unregistered fire arm and using a controlled weapon without excuse.
A 38-year-old Yangery man has been charged with 16 offences, including conspiracy, two counts of engaging in conduct that corrupts or would corrupt a betting outcome and animal cruelty.
A 27-year-old Warrnambool man has been charged with seven offences, including cruelty to animals and conspiracy to defraud racing stewards. A 31-year-old Warrnambool man has been charged with one count of using corrupt conduct information.
A police media spokeswoman said the charges were "part of an investigation into alleged illegal activity within the thoroughbred racing industry".
The charges have emerged from warrants executed at properties in Miners Rest and Warrnambool on January 30 this year.
A number of items, according to the media spokeswoman, including a firearm and what is believed to be conducted energy devices (jiggers) were seized from the properties.
All four men will appear at Melbourne Magistrates Court on 23 October.
Anyone with information about illegal activity is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report to www.crimestoppersvic.com.au