Gerry is right. Besides that, CIC checks our profile thru their own database, which is also linked with the US & many other 'conforming' nations, though that we had sent our PCCs.
For a non-conforming nation, they only do with the supplied PCC. However, if they have doubt, they might X-check with the Police/CID of that nation, as well. And sometimes they do it randomly too before issuing a SECDEC.