Conviction Based on DNA Report Unsafe Without Corroborative Evidence and Unbroken Chain of Custody: Gauhati High Court - 2025-09-15

Gauhati High Court Acquits Man in Rape-Murder Case, Cites Flawed DNA Evidence and Broken Chain of Circumstances

GUWAHATI: The Gauhati High Court has acquitted Passang Tashi @ Shanu, setting aside his life imprisonment sentence for the 2012 rape and murder of a 15-year-old girl. A division bench of Justice Robin Phukan and Justice N. Unni Krishnan Nair ruled that the conviction, based almost entirely on a positive DNA report, could not be sustained due to significant doubts over the collection and handling of forensic samples and the absence of a complete chain of circumstantial evidence.

Background of the Case

The case dates back to August 2012, when a 15-year-old girl went missing and was found dead the next day in a jungle area in Arunachal Pradesh. The post-mortem confirmed her death was a homicide caused by head injuries, with evidence suggesting sexual assault.

Following an investigation, Passang Tashi and several others were arrested. The trial court in Bomdila convicted Tashi under Sections 376 (rape) and 302 (murder) of the IPC, sentencing him to 10 years and life imprisonment, respectively. The conviction was primarily based on a Forensic Science Laboratory (FSL) report which found that Tashi’s DNA profile matched the sample from the victim's vaginal swab. All other co-accused were acquitted due to lack of evidence.

Appellant's Arguments: A Cloud of Suspicion Over DNA Report

In the appeal before the High Court, Tashi's counsel argued that the conviction was legally untenable as it rested on a single piece of evidence—the DNA report—which itself was mired in procedural lapses. The key arguments included:

* Broken Chain of Custody: The prosecution failed to establish an unbroken chain of custody for the biological samples from the point of collection to their analysis at the FSL. No seizure witnesses were examined, and there was no evidence on how the samples were stored and preserved.

* Procedural Irregularities: A second blood sample was collected from the appellant at the police station six months after the first, without independent witnesses, raising the possibility of contamination.

* Unexplained Delays: There was a significant, unexplained delay in sending the initial samples to the FSL, further compromising their integrity.

* Lack of Corroboration: Apart from the disputed DNA report, there was no other credible evidence, direct or circumstantial, to connect the appellant to the crime. No witness had seen him with the victim.

State's Defence and Court's Analysis

The State, represented by the Additional Public Prosecutor, contended that the DNA evidence was strongly corroborated by circumstantial evidence. This included the appellant being with other accused persons near the area on the day of the incident and his absence from home on the night of the crime.

However, the High Court undertook a meticulous review of the evidence and legal precedents. The bench cited the Supreme Court's landmark ruling in Sharad Birdhichand Sarda v. State of Maharashtra , reiterating that in cases based on circumstantial evidence, the chain of events must be so complete that it unerringly points to the guilt of the accused and excludes every other possible hypothesis.

The court observed:

"This chain of circumstances... cannot be said to be complete, as the prosecution side could not lead any evidence as to what had happened to the victim, when she parted with the company of the four Anis, after school hours... till recovery of her dead body on the next day morning."

On the crucial issue of the DNA evidence, the court referenced several Supreme Court judgments, including Manoj v. State of M.P. and Rahul v. State of Delhi , which held that while a DNA report is a valuable tool, its reliability depends on quality control and proper procedure. It is primarily a corroborative piece of evidence and cannot be the sole basis for conviction, especially when its collection is suspicious.

The judgment highlighted several critical flaws:

"Indisputably, the investigating officers, had not seized the samples so collected... Also there appears to be delay in sending the same to the FSL... No evidence was led as regard the chain of custody of the samples and its packaging, sealing and labeling... leaving enough space for the possibility of contamination."

Final Verdict and Implications

Concluding that the prosecution had failed to prove its case beyond a reasonable doubt, the High Court allowed the appeal. The bench noted that while the crime was heinous, suspicion, however strong, cannot replace legal proof.

The Court stated:

"In the result, we find sufficient merit in this appeal and accordingly, the same stands allowed. Conviction of appellant- Passang Tashi... stands set aside and quashed. Consequently, he shall be released from the custody, forthwith."

The judgment underscores the critical importance of maintaining procedural sanctity in collecting and handling forensic evidence. It serves as a strong reminder that even scientifically advanced evidence like DNA profiling is subject to judicial scrutiny and must be supported by a robust and unbroken chain of evidence to secure a conviction in a criminal trial. The court also directed the District Legal Services Authority to ensure that compensation under the state's victim compensation scheme is paid to the victim's family.