Military investigators are trying to determine the identity of a South Korean civilian whom the Defense Ministry said defected to the North after cutting through a border wire fence.

Three holes were found at the three-layer barbed wire fence in Yeoncheon at the western border with North Korea early Tuesday morning.

In announcing the results of its investigations on Tuesday, the Joint Chiefs of Staff Office said it had tentatively concluded the holes were probably cut by a Southern civilian, and were not the result of a North Korean intrusion, as initially suspected.

The Joint Chiefs of Staff are now conducting inquiries on reserve soldiers who have retired within the past decade, in consideration of the suspected border-crosser's apparent familiarity with the geography of the border area and the precision-style cutting of the wire fence.

The military is also cooperating with the police to determine if there are any missing persons among locals who were allowed passage into the border area, whose entrance is strictly off-limits to civilians.

The authorities mentioned a report of a 30-year-old man who had allegedly expressed his wish to defect to the North, but add that details of the report lacked credibility.

Pyongyang's failure to issue an official statement on the matter has also deepened the mystery surrounding the case.