Probable cause does not require an inquiry whether there is sufficient evidence to procure a conviction. It is enough that it is believed that the act complained of constitutes the offense charged. Thus, in determining the elements of the crime charged for purposes of arriving at a finding of probable cause, only facts sufficient to support a prima facie case against the (accused] are required, not absolute certainty.

REYES VS. OMBUDSMAN, G.R. NO. 212593-94, March 15, 2016; with accompanying cases G.R. Nos. 213163-78, 213540-41, 215880-94, 213475-76.

“x x x.

At the outset, it must be stressed that the Court has consistently refrained from interfering with the discretion of the Ombudsman to determine the existence of probable cause and to decide whether or not an Information should be filed. Nonetheless, this Court is not precluded from reviewing the Ombudsman's action when there is a charge of grave abuse of discretion. Grave abuse of discretion implies a capricious and whimsical exercise of judgment tantamount to lack of jurisdiction. The Ombudsman's exercise of power must have been done in an arbitrary or despotic manner which must be so patent and gross as to amount to an evasion of a positive duty or a virtual refusal to perform the duty enjoined or '1 to act at all in contemplation of law.145 In Ciron v. Gutierrez, 146 it was held that: 

This Court’s consistent policy has been to maintain non-interference in the determination of the Ombudsman of the existence of probable cause, provided there is no grave abuse in the exercise of such discretion. This observed policy is based not only on respect for the investigatory and prosecutory powers granted by the Constitution to the Office of the Ombudsman but upon practicality .as well. Otherwise, the functions of the Court will be seriously hampered by innumerable petitions assailing the dismissal of investigatory proceedings conducted by the Office of the Ombudsman with regard to complaints filed before it, in much the same way that the courts would be extremely swamped with cases if they could be compelled to review the exercise of discretion on the part of the fiscals or prosecuting attorneys each time they decide to file an information in court or dismiss a complaint by a private complainant.147 (Emphasis and underscoring supplied).

In assessing if the Ombudsman had committed grave abuse of discretion, attention must be drawn to the context of its ruling -that. is: preliminary investigation is merely an inquisitorial mode of discovering whether or not there is reasonable basis to believe that a crime has been committed and that the person charged should be held responsible for it. 148 Being merely based on opinion and belief, "a finding of probable cause does not require an inquiry as to whether there is sufficient evidence to secure a conviction."149 

In Fenequito v. Vergara, Jr.,150 "[p]robable cause, for the purpose of filing a criminal information, has been defined as such facts as are sufficient to engender a well-founded belief that a crime has been committed and that respondent is probably guilty thereof. The term does not mean 'actual or positive cause' nor does it import absolute certainty. It is merely based on opinion and reasonable belief. Probable cause does not require an inquiry xx x whether there is sufficient evidence to procure a conviction. It is enough that it is believed that the act complained of constitutes the offense charged."151 ' Thus, in determining the elements of the crime charged for purposes of arriving at a finding of probable cause, "only facts sufficient to support a prima facie case against the (accused] are required, not absolute certainty."152 

X x x.”