The Joint Civilian-Military Investigation Group, which South Korea established to investigate the sinking of its corvette, the Cheonan, in March, is expected to publish a final report this month. Much is riding on the document, which will be studied carefully by analysts in various countries, including China. The interim report in May concluded that the vessel was struck by a North Korean torpedo.
However, China and Russia have not accepted these findings and, even within South Korea, debate has been intense. A number of scholars, too, have cast doubt on the findings.
The three conclusions of the Joint Investigation Group (JIG) were rejected by a report, 'Rush to Judgment: Inconsistencies in South Korea's Cheonan Report', co-authored by Seunghun Lee, a physics professor at the University of Virginia, and J.J. Suh, director of Korea studies at Johns Hopkins University.
'After a careful analysis of the JIG's report and evidence and our own physical testing,' they write, 'we find that the JIG has failed (1) to substantiate its claim that there was an outside explosion; (2) to establish the causal linkage between the Cheonan's sinking and the torpedo; and (3) to demonstrate that the torpedo was manufactured by the DPRK [North Korea].'
Instead of accepting the JIG's report, they call for a new 'investigation that is as thorough, objective and scientific as humanly possible' in order to 'get to the bottom of the Cheonan incident to discover the cause and perpetrator'.
It now turns out that the JIG's final report may not be made public. That would be a mistake. For one thing, aside from South Koreans, the experts involved came primarily from Seoul's allies - the United States, Australia and Britain. Sweden was the only exception.
There has been no explanation as to why other experts, such as from China and Russia, were not invited to take part. Had they done so, their governments would have had difficulty rejecting the findings.
If the final report is to be credible, it should be made widely available so that its reliability would not be doubted. As it is, many questions remain. A simulation intended to show how a bubble might be formed by an underwater explosion - and how it might break a ship in two - had not been completed by the time the interim report was released.
Not all the investigators agreed with the conclusions. Shin Sang-chul, one of three experts recommended by the South Korean parliament to join the investigation, disagreed with the official findings. Shin, a former naval officer who had worked for seven years for a shipbuilding company, argued that the sinking was the result of an accident and accused Seoul of tampering with the evidence to lay the blame on North Korea.
Doubts have also been raised by the Lee-Suh team, which conducted its own study. Their report points to apparent inconsistencies in the official findings.
Evidence produced by the JIG linking North Korea to the Cheonan sinking included parts of a torpedo, with one fragment carrying ink markings in Korean. However, Lee and Suh pointed out that the outer part of the torpedo propulsion unit was extremely corroded, 'presumably because the coat of paint that would have protected the metal had been burnt off during the explosion'.
But, they say, 'ink has a lower boiling point, typically around 150 degrees Celsius, than paint does - typically 350 degrees Celsius', and so the ink marking should have burned away just like the outer paint.
They write: 'This inconsistency - the high-heat-tolerant paint was burnt but the low-heat-tolerant ink was not - cannot be explained, and casts serious doubt on the integrity of the torpedo as 'critical evidence'.'
In view of the many questions that have been raised, the final report needs to be of a very high standard indeed. If doubts remain, then a new investigation may have to be considered.
Frank Ching is a Hong Kong-based writer and commentator