The 2.5-mile-wide, 155-mile-long strip is fortified by wire fences, minefields and armed sentry posts.
The unnamed man, who is described as being in his late 20s, crossed into South Korea through the Demilitarized Zone (DMZ) at around 7 p.m. November 3, evading capture for 14 hours.
The Donga Ilbo news site reported on Monday that the still unidentified man's athletic background may have influenced his bold decision to make a run for the fence.
South Korean army soldiers patrol along a barbed-wire fence in Paju, South Korea, near the border with North Korea in June. Shortly after the incident, Seoul's Joint Chiefs of Staff (JCS) said there were no signs of significant damage to the fences where the man had crossed. It added that the barrier did not seem to have been cut or modified. He had been wandering an area strewn with land mines and claimed to be a civilian seeking to defect.
There has been strong criticism over the issue in the South as it's seen as a failure to respond to a potential North Korean infiltration.
Border guards had reportedly spotted the man crossing the barbed wire fence with a thermal observation device, however he was not arrested until many hours later.
The revelation came after Microsoft said early this month that hackers working for the Russian and North Korean governments have tried to break into the networks of seven pharmaceutical companies and vaccine researchers in Canada, France, India, South Korea and the United States.
North Korea repatriation is rare in the South, but according to the unification ministry about half of the 55 South Korean citizens confirmed to have left for the North in the past 10 years were defectors. Very few of the 31,000 who have fled do so via the DMZ, preferring instead to enter China then arrive in South Korea via a third country.
A defector who goes by the pseudonym Kim Gwang-hoon is one of several North Korean refugees who resettled in the South with hopes of a better life.