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In Canada this is probably possible. Whether they would actually implement your request is hard to know, but if you had good evidence someone would come here to commit a crime (and harming you would be criminal), it is hard to imagine that that fact wouldn't be considered in requests for a visa or requests to enter Canada.
The most productive direction for such requests would be through your Member of Parliament. A request could possibly also be made through Canada Border Services Agency.
I've not heard of it being done, but if your evidence is strong, I have confidence Canada would do what it could to prevent someone from entering Canada to conduct acts of ill will.
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As a (concerned) citizen, you can bring information to the attention of law enforcement agencies if you think that a crime or other illegal act did happen or is about to happen.
So if you were to overhear in a cafe, "he'll go to whereever on a tourist visa, but he'll really work in the kitchen of his cousin's restautant, the passport number is 1234 and the visa number is 4321," and you could make it credible that the information is genuine and accurate, that person might face pointed questions on immigration.
For a random citizen, the problem is twofold:
Take the occasional questions on Travel S.E. on how to break or circumvent rules. One could take the question and forward it to immigration authorities. "Here, look at that, ask NSA if they can match that IP to a real person, then you can deny/cancel the visa as appropriate."
Won't happen, of course. First, there are countless other things the immigrations authorities have to do, with much more solid evidence. Next, NSA has lots of data, but they won't release all they know to another agency (possibly even a foreign one) for such a minor matter.