Field for User who Validated the invoice / batch

I am creating a view which will allow me to peform some basic auditing of Invoices.  Among other information, in this view I would like to show who created the invoice, who validated the invoice, and who initiated the payment related to that invoice.  I have used the "last updated by" field of the AP_INVOICES_ALL and the AP_INVOICE_LINES_ALL tables but that only returned the user who modified an invoice prior to validation.  It did not return the user who validated the invoice. 

Thank you in advance for any help provided.