Section 140 — Closing an investigation: options
Statutory text (Thai original)
เมื่อพนักงานสอบสวนผู้รับผิดชอบในการสอบสวน เห็นว่าการสอบสวนเสร็จแล้ว ให้จัดการอย่างหนึ่งอย่างใดดังต่อไปนี้
(๑) ถ้าไม่ปรากฏว่าผู้ใดเป็นผู้กระทำความผิดและความผิดนั้นมีอัตราโทษจำคุกอย่างสูงไม่เกินสามปี ให้พนักงานสอบสวนงดการสอบสวน และบันทึกเหตุที่งดนั้นไว้ แล้วให้ส่งบันทึกพร้อมกับสำนวนไปยังพนักงานอัยการถ้าอัตราโทษอย่างสูงเกินกว่าสามปี ให้พนักงานสอบสวนส่งสำนวนไปยังพนักงานอัยการพร้อมทั้งความเห็นที่ควรให้งดการสอบสวนถ้าพนักงานอัยการสั่งให้งด หรือให้ทำการสอบสวนต่อไป ให้พนักงานสอบสวนปฏิบัติตามนั้น
(๒) ถ้ารู้ตัวผู้กระทำผิด ให้ใช้บัญญัติในสี่มาตราต่อไปนี้
English translation
When the responsible inquiry official is of the opinion that the investigation is complete, he shall take one of the following actions:
(1) If it does not appear who committed the offence and that offence carries a maximum penalty of imprisonment not exceeding three years, the inquiry official shall discontinue the investigation and record the reason for the discontinuance, then send the record together with the file to the public prosecutor. If the maximum penalty exceeds three years, the inquiry official shall send the file to the public prosecutor together with an opinion that the investigation should be discontinued. If the public prosecutor orders the investigation discontinued, or orders it to continue, the inquiry official shall comply.
(2) If the offender is known, the provisions of the following four sections shall apply.
This English translation is provided for reference only and has not yet been firm-verified — always rely on the Thai original.
Firm annotation
This section opens the closing stage of Chapter 1 on ordinary investigation. It sets the decision point once the responsible inquiry official concludes the fact-gathering is complete, splitting cases into unknown-offender and known-offender tracks. The known-offender track routes into sections 141 to 144, which govern how the file and the accused reach the public prosecutor. The three-year threshold allocates the shelving decision between the inquiry official and the prosecutor, keeping serious cases under prosecutorial control.
Why this matters in practice
Whether an investigation is validly closed matters because a defective closing can mean the prosecutor has no power to prosecute at all. Who counts as the "responsible" inquiry official is a recurring dispute, and Thai courts treat that as a question of fact rather than a pure point of law. If you are the accused or a complainant tracking a case at this stage, an early review of how the file was handled is worth a paid consultation before it reaches court.
Supreme Court decisions interpreting this section
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Supreme Court Judgment No. 1016/2567 (2024)
Which inquiry official in the locality is the responsible official empowered to summarize the file and give a prosecute/no-prosecute opinion under section 140 is a question of fact.
The accused argued the investigation was unlawful under section 140 and the prosecutor lacked power to prosecute under section 120. The Supreme Court held this was a dispute over which local officer was the responsible inquiry official, a factual question, so the further appeal was barred under section 218 paragraph one and was not accepted for adjudication.
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Supreme Court Judgment No. 4732/2560 (2017)
If the person who acted as responsible inquiry official had no legal authority to do so, the investigation is unlawful and the prosecutor has no power to prosecute.
Because the offence was not committed within the Kingdom in the relevant sense, the Attorney-General or acting head had no legal authority to act as responsible inquiry official, rendering the investigation unlawful, so the prosecution had no power to prosecute under sections 2(6), 18, 140 and 120.
Curated decisions with case numbers verified against the Supreme Court database. English renderings are the firm's editorial translation for study.
Frequently asked questions
What happens when a police investigation is complete?
Under section 140, the responsible inquiry official either discontinues the case where the offender is unknown and the offence is minor, or, if the offender is known, forwards the file to the public prosecutor to decide on prosecution.
Who decides to shelve a case where the offender is unknown?
If the maximum penalty is three years' imprisonment or less, the inquiry official may discontinue it; if it exceeds three years, the file goes to the public prosecutor, who decides whether to shelve or continue.