Is a taxpayer's Fourth and/or Fifth Amendment Constitutional Rights violated when the IRS civil revenue agent conducts a criminal investigation under the guise of a civil tax audit?

1. Is a taxpayer ’s Fourth and/or Fifth Amendment Constitutional Rights violated when the IRS civil revenue agent conducts a criminal investigation under the guise of a civil tax audit? 2. Should the civil IRS revenue agent be required to transfer the case over to the IRS Criminal Investigations Division once they have established firm indications of fraud like their manual and Unites States v. Peters 153 F.3d 445 (CA7 1998), as well as many other cases requires, in order to safeguard the taxpayers Fourth and Fifth Amendment Constitutional Rights? 3. If the civil IRS agents establish firm indications of fraud during a civil tax audit, and they do not refer the case to the IRS Criminal Investigations Division as required, should all evidence obtained from that point forward be suppressed?