What is the role of COA Auditors in appearing before the Court of Justice?

Instances where a COA auditor is required to appear in court include:

The Court of Justice or OMBUDSMAN sends Subpoena and Subpoena Duces Tecum, (as stated in Rule 23 Sec 1 Of the Rules of Court) to the auditor who undertakes the audit of transactions that are subject of a case.