Once CRA (the tax department) commences a criminal investigation of a taxpayer they must act in accordance with the Canadian Charter of Rights and Freedoms.
"This article provides information of a general nature only. It is only current at the posting date. It is not updated and it may no longer be current. It does not provide legal advice nor can it or should it be relied upon. All tax situations are specific to their facts and will differ from the situations in the articles. If you have specific legal questions you should consult a lawyer."