Before many kids chow down on their trick-or-treat haul tonight, their parents will be checking the stash to ensure none of the candy has been tampered with.

Last Halloween, there were reports of candy tampering across the country, in places such as Cape Breton, Toronto, Winnipeg, Grande Prairie, Alta., and Lloydminster, Sask. In Halifax, there were five reports in 2014 and 2015, according to Halifax Regional Police.

Not surprisingly, police forces generally recommend parents inspect their children's candy.

But for Joel Best, the world's leading authority on poisoned Halloween candy — and possibly the only authority on the subject — such precautions aren't necessary.

"There's no evidence that this is happening and yet we like the story. We like the idea that it's scary," said the sociology and criminal justice professor at the University of Delaware.

No motivation

As a graduate student in the early 1970s, he studied deviant behaviour and read autobiographies by thieves and drug addicts. One thing that stood out to him was that these people explained why they did what they did.

At the time, there were a lot of news stories about Halloween candy tampering. Best asked himself why someone would do such a thing and he couldn't come up with a reason. So he started tracking incidents, searching as far back as 1958. He still collects data today as a hobby.

By the early 1980s, he reached a conclusion, which hasn't changed.

"I have yet to find of a report of an incident where a child was killed or seriously injured by a contaminated treat picked up in the course of trick-or-treating," said Best.

While he won't say all of the cases are hoaxes, he maintains the vast majority are.

Attention seeking

Best believes kids are behind most incidents.

"Claiming to have received a contaminated treat is a way of getting the concerned attention of adults who are going to treat you respectfully. They're going to treat you like a victim, rather than like a troublemaker," he said.

Given mischief and fear are critical elements of Halloween, Best said it makes sense this is one of the pranks pulled.

Halloween sadist

Best finds it absurd there's a narrative of a Halloween sadist out to poison children or stick pins in their chocolate bars.

"This is a guy who is so crazy that he kills little children at random but he's so tightly wrapped, he only does it one night a year," Best said.

While there have been reports of children who died from eating tainted Halloween candy, Best said police and coroner investigations later determined those to be false.

Joel Best

Academic Joel Best says it was a point of pride for him to not check his children's candy. (University of Delaware)

In 2001, a B.C. toddler became ill after trick-or-treating with siblings and died in hospital of heart failure. Some people speculated the girl might have eaten tainted candy, but a coroner performed an autopsy and found no signs of poison in her body.

Of the five alleged incidents in 2014 and 2015 in Halifax, none of the cases resulted in charges laid. Halifax police doubt the cases were hoaxes.

"People came forward with concerns, so I wouldn't say they were a hoax. We always believe our citizens when they come forward with these cases," spokeswoman Const. Dianne Woodworth said.

Tough to investigate

Investigating the cases is difficult.

"We don't have a specific location, so we can't target a certain person because it's a wide variety of houses. We don't know exactly where it came from. Did it happen in the store? It is very difficult because it broadens your investigative area," Woodworth said.

Best said when his kids were trick-or-treating, it was a point of pride for him to never check their candy.

"I just figured, if you believe what you're doing [in the research], just let it happen," he said.