Andy Brewin's two dogs died of poisoning after chewing on carcasses in a ditch. ((Tom Taylor/CBC))

A man in Tecumseh, Ont., is offering a $2,500 reward to anyone who can help him figure out who was responsible for the death of his two dogs in early November.

Andy Brewin's boxers, Boomer and Griss, died on Nov. 8, just 20 minutes after chewing on a deer carcass in a ditch in Essex, a rural farming community. Earlier reports had suggested the dogs died after drinking from the ditch.

An autopsy conducted by Ontario's Environment Ministry last month determined they were poisoned by high levels of carbofuran, a pesticide used to control insects in vegetable and fruit crops. The ministry stressed in its findings that carbofuran is legal, and that local farmers had committed no violations.

Not satisfied with those results, Brewin and his wife conducted their own investigation.

"I got some kitchen gloves and a hacksaw and cut a piece [of one of the deer carcasses] off," Brewin told CBC News. "My wife dropped it off at the University of Guelph, and the pathologist ... did the sample for free, and it came back positive [for] pesticides."

That finding does not contradict the ministry's finding.

Criminal charges warranted: owner

Brewin believes somebody left the poisoned carcasses in the ditch on purpose to keep predators from wandering onto his or her fields. That's grounds for criminal charges, Brewin said, citing sections 444 and 445 of the Criminal Code of Canada, which prohibit the endangering of cattle and other animals.

He hopes the reward will encourage people with knowledge of the carcasses to come forward.

"I hope the person [who left the carcasses] would really contemplate their actions," Brewin said.

"I understand you have to grow your crops, but to the cost of family pets?" Brewin asked. "What's the trade-off here?"

Though the Environment Ministry said its investigation is closed, the provincial Ministry of Natural Resources has contacted Brewin to say it will continue to investigate the incident, Brewin said.

Ontario Provincial Police have told Brewin it cannot investigate an alleged crime without sufficient evidence.

The Brewins have bought a new dog: a new boxer named Piper.