The South Korean government released this report on September 13, 2010. The preface states,
"On March 26, 2010, an unprecedented incident in which ROKS Cheonan was sunk by a surprise torpedo attack by a North Korean submarine occurred, resulting in the death of 46 crew members.
The Ministry of National Defense organized the Civilian-Military Joint Investigation Group on March 31 in order to clearly identify the cause of the sinking as well as the entity responsible for the incident. The Civilian-Military Joint Investigation Group proceeded with the investigation with the participation of civilian and foreign experts to ensure objectivity and credibility.
The Civilian-Military Joint Investigation Group conducted its investigation while the whole group was lodging near the incident site in the West Sea facing unfavorable conditions such as harsh climates and currents. Despite these difficulties, its objective and scientific investigation found that ROKS Cheonan was sunk due to a torpedo launched by a North Korean midget submarine. The final investigation results were announced on May 20.
The Civilian-Military Joint Investigation Group reported the investigation results to the UN Security Council on June 14. As a result, UN Security Council Presidential Statement that acknowledges and condemns North Korea’s culpability in the incident was unanimously adopted.
Nonetheless, North Korea continues to deny the facts and has heightened its threats of military provocations, claiming that the Republic of Korea fabricated the investigation results. Even within the Republic of Korea, the reality is that there are individuals who raise doubts against the investigation results based on their own interests, and they are taking irresponsible actions such as spreading groundless assertions.
Thus, the Ministry of National Defense has published the Joint Investigation Report on the Attack Against ROK Ship Cheonan, which contains the findings of the Civilian-Military Joint Investigation Group and the evidence data in both Korean and English in order to inform Koreans and the international community of the truth, and to resolve unnecessary misunderstandings and suspicions.
...This is one of the world’s first reports on an investigation of a salvaged hull of a warship that was sunk by a torpedo. The finding of the propulsion motor of a torpedo(the smoking gun) and the detection of explosive components illustrated to the North and the international community that even the most covert of attacks will leave evidence behind. Most importantly, all this entails a solemn warning to the North not to engage in further military provocations."