Ten North Koreans who were being investigated after their wooden boat was impounded by the coast guard off the northern coast of Hokkaido island, Japan, on Thursday, admitted they stole home appliances from a refuge hut on an uninhabited islet.

Japanese authorities and the coast guard began questioning the fishermen after they received complaints of things like TV, refrigerator and rice cooker going missing from a shelter in the nearby area, which was locked but was broken into.

"Everything has gone. Everything. Including door hinges and a door knob, everything made of metal has gone," said Shusaku Yoshida, the caretaker of a shelter for local fishermen, Sky News reported. “Two TV sets, three fridges, a washing machine, an oven/microwave, two stereo sets, a DVD/CD player, an electric saw, a stove (heater), coal, a motorbike and a generator. In addition, solar panels, an anime poster and blankets were stolen," he said.

The North Korean fishermen became prime suspects in the eyes of the investigators after the coast guard found them dumping some appliances and other items into the sea before their vessel was impounded near the Japanese coast Sunday. According to investigative sources, some of the objects dumped by them were later collected by the coast guard, Kyodo News reported. 

There is a possibility that the 10 fishermen were employed by the North Korea military, since a plate hanging in their boat read: “Korean People's Army No. 854 military unit.” It is not uncommon for North Korean army men to take up fishing and farming as a part-time profession.

At the time the fishermen had mentioned that they had drifted shore from the Sea of Japan after their steering wheel failed in the middle of their squid fishing expedition. According to sources, the local police found squid and fish nets on the boat, but no weapons.

Cases of North Korean fishermen boats drifting ashore on the Sea of Japan coast are increasing at an alarming rate, with November alone recording 28 such instances — the highest in the last four years.

On Tuesday, Keiichi Ishii, Japanese Minister of Land, Infrastructure, Transport and Tourism said, "We are raising the alert level along Sea of Japan coastal areas ... We will take full measures to ensure security in territorial waters."

On Nov. 23, police found eight North Korean fishermen standing around at the seaside in Yurihonjo, Japan, with their boat found near the town’s marina.

When they were questioned about how their vessel had steered into the Japanese islet, they told investigators they had left the port of Chongjin in the northeast of North Korea in September for fishing in the Sea of Japan and after a while "they were drifting because they were caught in a squid."

The Japanese government said at the time that the men will be allowed to return to North Korea once their identities are verified and they still wished to return to their home country.

Chief Cabinet Secretary Suga Yoshihide later said in a press conference, “We are investigating men and we will respond appropriately together with related organizations.”

Asked about the possibility that these men were North Korean spies, he said, "We are looking carefully at the situation, including that."

North Korea In this photo, Japan coast guard officers check a small wooden boat (L) which carried nine North Korean detectors, at Kanazawa port in Ishikawa Prefecture, central Japan on Sept. 13, 2011. Photo: Getty Images