Oct. 31 (UPI) -- A South Korean fishing vessel that went missing Saturday in North Korea waters spent 20 hours north of the maritime border before crew members were detained, Seoul's defense ministry said Tuesday.
Defense Minister Song Young-moo said during a South Korean parliamentary audit the fishermen aboard the 391 Heungjin engaged in fishing activity north of the border before they were apprehended on Saturday.
Song was reporting results from an initial investigation into the boat conducted Sunday, two days after North Korea repatriated the crew.
Ahead of the boat's release last week, Pyongyang's state news agency KCNA had said the South Korean fishing vessel had "illegally infiltrated our waters of the East Sea."
"After inspections we found the fishing vessel and its crew had trespassed into our waters in order to catch fish," KCNA said.
Song said Tuesday the fishermen were required by North Korean authorities to sign a letter acknowledging their "infiltration" of the North prior to their release.
The South Korean defense minister said investigation is ongoing into whether the crew turned off their GPS after they trespassed into North Korean waters.
EDaily reported Seoul is investigating reasons why the captain of the 391 Heungjin did not contact the South Korean coast guard at the time of the boat's capture in North Korea.
"The captain of the 391 Heungjin did not contact the coast guard nor the fisheries information bureau," said a member of a government joint-investigations team.