Santanee Ditsayabut is a Senior Expert Public Prosecutor from the Office of the Attorney General of Thailand.
After more than 25 years as a public prosecutor, I still occasionally find myself reflecting on old cases and asking a simple but important question: Did we really get to the truth?
As prosecutors, we spend our careers assessing evidence, reviewing investigation files, and deciding whether a case should proceed to court. And when it does, we stand before the court to present evidence that leaves no doubt that the defendant is guilty.
In many criminal cases, a confession is often regarded as the strongest piece of evidence. Once a confession appears in the investigation file, the burden of uncertainty seems to diminish. The question that is seldom asked is: How was that confession obtained?
This question carries real professional weight. When a prosecutor has doubts in evidence secured by the police, but the file contains a signed confession, deciding not to prosecute becomes very difficult. In practice, the doubt does not fall on the accused but it falls on the prosecutor. How can you not have an indictment? The institutional pressure to move forward with an indictment is strong, and often unspoken.
In court, defense lawyers would routinely ask defendants whether they had been mistreated during the inquiry process. Many answered “yes.” However, these exchanges were frequently treated as a procedural formality rather than serious allegation before the Court that requires scrutiny what had actually happened. They became part of the routine of criminal proceedings rather than part of the search for truth.
When the File Did Not Match
Over the years, I came across cases that challenged my assumptions. I remember meeting a defendant accused of premeditated killing of his wife and finding myself hard to connect the person sitting before me with the story told in the case file. In other cases, particularly those involving sexual violence, sometimes I struggled to understand why victims behaved in ways that seemed inconsistent with common expectations, even though I believed what they said. Human behavior is complex. Memory is not like a recording. Trauma changes how people remember, speak, and carry themselves. But the criminal justice system is rarely built to take this into account.
These experiences kept bringing me back to the same question: Could there be a better way to find the truth? The way that would help investigators obtain reliable information, support fair decision-making, and provide a clear framework for what effective questioning should—and should not—look like.
A Framework that Made Sense
Until 2020, I was invited to involve with the draft Principles on Effective Interviewing for Investigations and Information Gathering — widely known as “the Mendez Principles.” Serving on the Advisory Council, in my capacity to review and comment on the draft text, proved to be a turning point in my professional thinking.
What immediately appealed to me was that the Principles did not promise anything extraordinary. Instead, they brought together human rights standards, scientific research on memory and cognition, and practical investigative techniques into a coherent, evidence-based framework. This is not ideology, but it is a practical approach designed to work effectively in the real world.
The Principles helped explain many of the questions I had carried for years in my practice. Why do people remember the same event differently? Why might a child provide inaccurate information without any intention to lie? Why can pressure and coercion distort the information we receive? And why is torture not only unlawful and unethical, but also unreliable as a means of discovering the truth?
From Principles to Practice: the Thai Context
Many of the standards embedded in the Principles already reflected in Thai law, including safeguards enshrined in the Constitution and the Criminal Procedure Code. The emergence of the Mendez Principles ,which is in line with investigative interviewing approach, also coincided with an important development in Thailand: the enactment of the Prevention and Suppression of Torture and Enforced Disappearance Act, 2022. Together, these developments created a momentum for promoting professional, rights-based interviewing practices within the criminal justice system in Thailand.
Since then, I have dedicated much of my work at the Nitivajra Institute — the justice innovation unit of the Office of the Attorney General of Thailand — to advancing these ideas intoThai criminal justice system. In 2023, in partnership with the Association for the Prevention of Torture (APT), we supported the publication and dissemination of the Thai translation of the Mendez Principles. Also together with the Thailand Institute of Justice (TIJ), the Norwegian Centre for Human Rights (NCHR), the New Zealand Police, and APT, we have developed yearly training programmes on investigative interviewing for prosecutors and law enforcement officials from the Royal Thai Police, the Department of Special Investigation, as well as the Ministry of Interior.
The response has been overwhelmingly encouraging. Participants often tell us that the approach makes sense—not only because it aligns with human rights standards, but because it makes them do their jobs more effectively. Most recently, in May 2026, this work too another step forward when we collaborated with UNODC, TIJ, and NCHR to launch the Thai version of UNODC e-Learning module on Investigative Interviewing to help broaden access to these new international standards across the country.
The Road Ahead
Of course, training alone cannot accomplish the goal. It is only one dimension of change. Real reform requires organizational support, leadership commitment, and sufficient time for a new mindset to take hole that, after all, the purpose of an interview is not to obtain a confession. It is to obtain accurate and reliable information.
Our next step is to pilot the implementation of investigative interviewing approaches at the provincial level and learn from practice. We know that change does not happen quickly. But if we continue to do things the same way, we cannot expect different results.
As a prosecutor, our professional calling is not simply to win the cases. The most fundamental duty of a prosecutor is to present reliable evidence in the pursuit of truth and to ensure that justice is genuinely served. I am deeply convinced that Investigative Interviewing is a method through which the presumption of innocence is not merely a legal principle written in law — it becomes something real and visible in practice. When we commit to this approach, we hold the power to prevent and eliminate miscarriage of justice, which is perhaps the most profound injustice that a society can ever inflict upon one of its own.
