A Securitization Audit is an audit done by a third party researcher who scours through various publicly available resources (such as EDGAR: an SEC database) to find proof that your loan was securitized (meaning your loan was pooled with other loans and sold to investors).
Often, a well trained auditor can pinpoint the actual location of your loan among hundreds of thousands of investments. This is tedious and grueling work, as they have to literally find a needle in a haystack of a few thousand loans.
What a Securitization Auditor would provide you at the end of a Securitization Audit
is a multi page document that is admissible in court as evidence. The document will show whether your loan was securitized and in some cases what investor pool your loan is in, or what Trust it belongs to.
Since this information is publicly available through the SEC, the affidavit is a simple statement of fact (given with firsthand knowledge) that your loan has been securitized.
Other things the auditor will look at are recorded documents such as a Mortgage Assignment, Substitution of Trustee, Notice of Trustee sale and other recorded documents and investigate those who signed those documents.