The wreckage of a boat authorities believe originated from North Korea has been discovered washed up on the shores of the Japanese island Sado, on Friday, Dec. 27. It contained the remains of up to seven people.

Some bodies found on the boat were “partially skeletonized,” suggesting the victims may have been deceased for quite some time. The coast guard and law enforcement officials made the discovery on Saturday, as conditions were too poor on the previous day to examine the remaining bow of the boat.

Wooden boats from North Korea often wash up on Japan’s shoreline. (Screenshot NHK)

The remains of the five victims included two decapitated heads as part of the gruesome find. It had not been determined if the heads belonged to the bodies, reports Fox News.

The “ghost ship” bearing Korean red lettering and numbers on the side, most likely floundered in the rough winter waters of the Sea of Japan and ended up off the coast of Japan’s northwestern prefecture of Niigata.

A part of a boat on Sado Island, Niigata Prefecture, northern Japan, on Dec. 28, 2019. The boat suspected of being from North Korea with several bodies was found on the small island, the Japanese coast guard said on Dec. 29, 2019. (Sado Coast Guard Station via AP)

Japanese public broadcaster NHK reported that the wooden boat, measuring 24. 9 feet (7.6 meters) long, 14 feet (4.3 meters) wide, and 6.5 feet (2 meters) high, is but one of many “ghost ships” from North Korea that end up on Japanese beaches.

The voyage from North Korea to Japan is a long, arduous one, and the boats are often ill-equipped to make the journey.

NHK reports coast guard officers say many wooden boats wash ashore after strong northwesterly winds blow them off course.

North Korean shipping boats, which are usually poorly equipped, are believed to be under pressure to catch more fish for the nation’s food supply and are wandering farther out to sea. Sometimes North Koreans are found alive on such boats and have been deported, reports The Associated Press.

Ties between the two countries have been tense lately, on Friday, NHK issued an apology after falsely reporting North Korea had launched a missile that had fallen into the sea on the east of the Japanese archipelago. They apologized and said it was a training alert for the media.

Includes reporting from The Associated Press