G.R. No. 125303 - Leonardo vs. National Labor Relations Commission

Petitioners, comprising senior officers and personnel from the Finance Service of the Philippine Army, filed a certiorari and prohibition petition.
They sought to prevent the then Provincial Fiscal of Rizal, Benjamin H. Aquino, from conducting a preliminary criminal investigation into allegations of malversation through the falsification of public, official, and commercial documents.
The petitioners argued that once vouchers had been finally approved by the Auditor General—and such approval was rendered final and irrevocable—not even the courts could substitute its findings by permitting a criminal inquiry.

Petitioners claimed that allowing the Provincial Fiscal to investigate criminal liability would encroach on the constitutional prerogatives of the Auditor General.
They relied on the constitutional mandate which vests the Auditor General with the duty to examine, audit, and settle all government accounts, as well as the specific power to “bring to the attention of the proper administrative officer expenditures of funds or property which, in his opinion, are irregular, unnecessary, excessive, or extravagant.”
They further argued that Section 657 of the Revised Administrative Code, by establishing the finality of settled accounts, effectively precluded any further inquiry into the correctness of the vouchers from a criminal perspective.

On June 6, 1967, the petitioners initiated the certiorari and prohibition proceeding challenging the jurisdiction of the Provincial Fiscal.
The Provincial Fiscal denied the petitioners' motion to quash his authority via a resolution on May 23, 1967, asserting that his role to investigate possible criminal offenses did not conflict with the Auditor General’s administrative function.
A subsequent motion to dismiss filed by the Provincial Fiscal on November 2, 1967, argued that even if the amounts in question were from settled accounts, there remained no legal barrier to instituting a criminal investigation without the need for any certification by the Auditor General.
After opposition by the petitioners, the lower court, on December 20, 1967, dismissed the petition on the basis that the investigation by the fiscal was a proper exercise of his prosecutorial function and that an injunction against a criminal investigation would be contrary to established law.
The case was elevated on appeal to the Supreme Court on January 3, 1968, with the petitioners arguing a breach of constitutional limits on the investigative power, and the respondents defending the Fiscal’s authority.

Does a preliminary investigation conducted by a provincial fiscal into alleged malversation through the falsification of public documents encroach on the constitutional prerogatives reserved for the Auditor General?

Can the finality clause, which renders vouchers, claims, or accounts "once finally settled" immune from further review except under prescribed circumstances, be interpreted to bar a criminal investigation?
Does Section 657 of the Revised Administrative Code imply that the Auditor General’s powers extend to determining criminal liability for anomalies discovered during the audit, thereby precluding fiscal investigation?

Is it appropriate for the courts to issue a writ of prohibition to restrain a fiscal from instituting a preliminary criminal investigation, considering the separation of powers and established judicial doctrine?