Upholding Conviction In Drug Sale Ensuring Chain OF Custody IN Evidence Handling

The Supreme Court’s 2014 decision in People v. Constantino, Jr. (G.R. No. 199689) is a powerful reminder that in drug cases, the prosecution’s job does not end with proving that a sale took place. The seized drugs themselves — the corpus delicti — must be shown to be the very same items confiscated from the accused. When the chain of custody is broken, even a seemingly solid buy-bust case can collapse.

The Buy-Bust and the Conviction

On January 20, 2005, police in Tuguegarao City conducted a buy-bust operation against Hermanos Constantino, Jr., who allegedly sold two sachets of shabu to a poseur-buyer for P1,000. The Regional Trial Court convicted him of illegal sale of dangerous drugs under Section 5, Article II of Republic Act No. 9165, sentencing him to life imprisonment and a P500,000 fine. The Court of Appeals affirmed.

The Issue: Who Marked the Drugs?

The defense argued that the prosecution failed to establish the chain of custody of the seized drugs. The Supreme Court agreed, focusing on a critical first step: the marking of the seized items.

Under Section 21 of R.A. 9165 and its Implementing Rules, seized drugs must be physically inventoried and photographed immediately after seizure, in the presence of the accused, a media representative, a DOJ representative, and an elected public official. Non-compliance may be excused under justifiable grounds, but only if the integrity and evidentiary value of the seized items are preserved.

The chain of custody requires that every person who handled the evidence testify about how and from whom it was received, and what happened to it while in their possession. In a buy-bust, the links are: (1) seizure and marking by the apprehending officer; (2) turnover to the investigating officer; (3) turnover to the forensic chemist; and (4) turnover to the court.

The Fatal Inconsistencies

Here, the prosecution’s own witnesses gave conflicting accounts of who marked the sachets “NBT”:

• PO3 Domingo (poseur-buyer) said the investigator, SPO2 Tamang, placed the markings at the police station.
• PO3 Hernandez said SPO2 Taguiam placed the markings after the operation.
• Forensic Chemist P/SInsp. Tulauan said the markings were made by SPO3 Tamaray, the duty officer at the crime laboratory.

The Court found these contradictions “glaring.” The poseur-buyer, who had immediate custody of the sachets, failed to mark them on the spot. Three different people supposedly marked the same items at different times. The prosecution did not present SPO2 Tamang or SPO2 Taguiam to clarify the matter.

Why Marking Matters

Marking the seized item immediately after seizure is the starting point of the custodial link. It separates the evidence from all other similar items and prevents switching, planting, or contamination. A failure to mark at the time of initial custody “imperils the integrity of the chain of custody.”

Because the prosecution could not establish that the sachets presented in court were the very ones taken from Constantino, the Court reversed the conviction and acquitted him — not because it believed his frame-up defense, but because the prosecution failed to prove guilt beyond reasonable doubt.

Practical Takeaways

• Mark evidence immediately. The officer who first takes custody of seized drugs should mark them at the scene, not later at the station.
• Document every transfer. Each person who handles the evidence should be able to testify about receiving and delivering it, with dates and times.
• Present all links in the chain. Do not omit witnesses who can confirm markings and custody, even if their testimony seems routine.
• Non-compliance is not automatically fatal, but the prosecution must explain it and show that the evidence’s integrity was preserved.
• Inconsistencies on core facts are costly. Conflicting testimony about who marked the drugs — a basic detail — can destroy an otherwise strong case.

This article is general information and not legal advice. For your specific situation, consult a lawyer or ask ASG Legal AI.