泳およがせ捜そう査さ

noun

controlled delivery; arm's-length surveillance

A law-enforcement tactic where authorities allow a suspect to continue illegal activity under surveillance in order to gather evidence or identify accomplices.

• 警けい察さつは泳およがせ捜そう査さで密みつ売ばい組そ織しきの全ぜん容ようを解かい明めいした。

  The police uncovered the full scope of the trafficking ring through a controlled delivery operation.