Typically, when someone arrives at a port of entry, there may be a flag in the CBSA port of entry system. The CBSA officer would then take the person to secondary and investigate. CBSA officers are well trained to pick up on indicators when they interview people at the booths or in what people say. That's one way to have that happen.
All that said, if IRCC becomes aware of someone who has entered into a pathway in the immigration system and there are questions about that person's genuineness, whether that person may have committed fraud, we can launch what's called a level one investigation, or we pass it over to our enforcement arm, the CBSA, which enters into a criminal investigation or what we call a level two investigation.
It all depends on the circumstances and where that person is in the immigration system or continuum. Then we can take the various means to look at the situation, but we always investigate first—or other parts of the government investigate first—to determine what's happening.