How can we monitor or report when the Expense Auditor changes an Expense item amount?

Summary:

Can we monitor through a query, standard report, or OTBI report if a the value of an expense item has been changed by the Expense Auditor?

If so, please provide the report name (if standard is available) or field name in db or otbi subject area, that would allow us to build a report around.

Content (required):

Our requirement is for the Auditor to reject or approve, not change an expense report. There is no functionality to prevent the Auditor from changing the amount, so the next best thing is to try and monitor any changes.

Version (include the version you are using, if applicable):