In the Philippine legal system, Murder is classified as a heinous crime under Article 248 of the Revised Penal Code (RPC). Unlike Homicide, Murder involves specific qualifying circumstances that demonstrate a higher level of perversity or cruelty. Navigating the process of filing a complaint requires a clear understanding of the legal requirements, the stages of prosecution, and the necessary evidence.

I. Defining Murder under Philippine Law

Before filing, it is crucial to distinguish Murder from Homicide. Under Article 248, any person who kills another shall be guilty of murder if the killing is committed with any of the following qualifying circumstances:

Treachery (Alevosia): Taking advantage of superior strength, with aid of armed men, or employing means to afford impunity.
In Consideration of a Price, Reward, or Promise.
By Means of Inundation, Fire, Poison, Explosion, or Stranding of a Vessel.
On the Occasion of a Calamity: Such as an earthquake, eruption, or epidemic.
With Evident Premeditation: A deliberate plan to kill.
With Cruelty: Deliberately and inhumanly augmenting the suffering of the victim.

If none of these circumstances are present and proven, the charge may be downgraded to Homicide.

II. Step 1: Gathering Essential Evidence

A complaint will not move forward without a "prima facie" case. You must compile the following documents:

Affidavits (Sinumpaang Salaysay): Sworn statements from eyewitnesses or persons with personal knowledge of the incident.
Death Certificate: To prove the fact of death.
Autopsy/Medico-Legal Report: Provided by the PNP Crime Lab or NBI to determine the cause of death and the nature of the wounds.
Police Report/Blotter: The initial record of the incident from the local police station.
CCTV Footage or Photographs: If available, to establish the presence of the accused at the scene.

III. Step 2: The Filing Process (Preliminary Investigation)

The criminal action typically begins with the filing of a Complaint-Affidavit before the Office of the City or Provincial Prosecutor where the crime was committed.

1. Filing the Complaint-Affidavit

The complainant (usually the victim's next of kin) submits the affidavit, subscribed and sworn to before a prosecutor or any government official authorized to administer oaths.

2. Preliminary Investigation (PI)

The Prosecutor conducts a PI to determine if there is probable cause—a well-founded belief that a crime has been committed and the respondent is probably guilty thereof.

Subpoena: The Prosecutor issues a subpoena to the respondent, attached with the complaint.
Counter-Affidavit: The respondent is given ten (10) days to submit their defense.
Clarificatory Hearing: The prosecutor may call both parties for questioning if certain facts remain unclear.

3. The Resolution

The Prosecutor will issue a Resolution.

If Probable Cause exists: An "Information" (the formal criminal charge) is filed in the Regional Trial Court (RTC).
If No Probable Cause exists: The complaint is dismissed. The complainant may file a Motion for Reconsideration or a Petition for Review with the Department of Justice (DOJ).

IV. Step 3: Arrest and Inquest (Special Circumstances)

If the suspect was caught in the act or immediately after the crime (Hot Pursuit), the process changes:

Inquest Proceedings: An informal and summary investigation conducted by a public prosecutor in criminal cases involving persons arrested and detained without a warrant.
Warrant of Arrest: In regular filings, once the Information is filed in court, the Judge examines the records and, if satisfied, issues a Warrant of Arrest. Murder is a non-bailable offense when evidence of guilt is strong.

V. Key Legal Principles to Remember

Principle	Description
Presumption of Innocence	The accused is presumed innocent until proven guilty beyond a reasonable doubt.
Burden of Proof	The prosecution carries the burden of proving every element of the crime.
Jurisdiction	The case must be filed in the RTC of the city or municipality where the killing occurred.
Prescription Period	The crime of Murder prescribes in 20 years. However, once a complaint is filed with the prosecutor's office, the running of the prescriptive period is interrupted.

VI. The Hierarchy of Prosecution

The path of a Murder case follows these stages:

Law Enforcement: Investigation and evidence gathering.
Prosecution: Preliminary Investigation and filing of Information.
Courts: Arraignment, Pre-trial, Trial, and Judgment.
Corrections: If convicted, the perpetrator serves the penalty of Reclusion Perpetua (20 years and 1 day to 40 years) at the Bureau of Corrections (BuCor).

VII. Challenges and Delays

Filipino litigants should be prepared for the "clogged dockets" of the judiciary. A murder trial can take several years. It is highly recommended to engage a private prosecutor (a private lawyer) to represent the interests of the victim's family and assist the public prosecutor in handling the case.