Success With CIC Informant Line?

[somethingsomething]

I report a case of fraud where someone obtained their PR in Canada after misrepresenting documents and his application. I have sent them relevant documents and provided all his information to them, but I was told they can't do much about in the past and need to catch her in the act. Does this mean that because she received her PR status, that they will only investigate what she may currently be doing?

As well, does anyone know how quickly the CIC respond to informant tips, if given solid information?

Thanks