An article in CBC news suggests that perhaps naval officer Jeffrey Delisle was spying for Russia. Delisle is accused of giving secret material to a foreign entity.
The article points out that four Russian diplomats have had their names removed from a list of those recognized by Canada. However on reading the details of the article it is not really clear that the removal was related to the spying case.
Two of those involved were leaving in any event simply because their terms were up. However two others had their credentials revoked after the announcement of the arrest of Delisle. Canada has made no comment on the issue. Russian media quotes the Russian foreign ministry as surprised at Canadian reports since two of the diplomats were finishing their terms in Canada.
This does not address the issue of the other two individuals. Some commentators expressed skepticism that the Russian embassy personnel would be involved in spying. One analyst said that the Russian embassy would be the last place to pick to run a spy operation.
However, embassies collect information as part of their job. Certainly U.S. embassies especially in places such as Pakistan are noted for having spies on staff. I see no reason to think that Russia would not act in a similar manner. Obviously neither Russia nor Canada wants to make an issue of this event and will be happy to see any media coverage fade away.