Judging from the number of journalists in the room today, it's clear that they monitor very closely the actions of the Ethics Commissioner.
Before you even announce your plans to conduct an inquiry, would it not be advisable, strictly from an information standpoint, to contact the MP or the minister concerned to let him or her know what you're intending to do? You might have some questions concerning the information you received. I don't know if I've explained myself clearly, but the lawyer in me feels that simply saying that you have received information and that you will conduct an inquiry could cause more harm than anything else.
In short, shouldn't you raise the matter first with the member or minister concerned?