If you really are that concerned you need to report the info directly to the CIC as I believe was advised before if need be they will likely advise the CBSA and/or issue a letter themselves stating the person misrepresented themselves and go from there. If you have reported the info to the authorities involved, your part is pretty much complete unless they have further questions plus they won't act on it right away (i.e you won't see them deported or whatever action is to be taken) in mere days, this takes a while as they have many cases to deal with. You'll have to be patient.