shingeye zimnyoka, bbc news.ng the heavily fortified borderfrom neighbouring north korea. our seoul correspondent, laura bicker, joins me now. what do we know about this individual? this all took place in the early hours are monday morning, under the cover of darkness. it appears that the north korean man swam from north to south, remember, this is a five mile heavily fortified border so it looks like it's across the maritime border and hit land and made his way through a tunnel, some kind of drainpipe, underneath the barbed wire on the beach and then slowly tracked his way south and found at a checkpoint. within the restricted area of the border. this all comes from the joint chiefs of staff, releasing details today and say that they are launching an investigation because they monitored the movement for three hours and troops did not act quickly enough and they are looking at this drainpipe to see if they can perhaps lock it more than it has been already —— block at. it has been already -- block at. . ., . , �*