Remains recently found in Chiba Prefecture have been confirmed to be those of a man who disappeared at sea in 2004 and was subsequently listed by a private group as a potential kidnapping victim of North Korea, the police said Saturday.

The family of Shuji Koyama, a Niigata resident who went missing in the Sea of Japan on June 6, 2004, while fishing off the city’s coast around dawn at age 43, was told Saturday the remains are almost certainly his, after senior police officials visited to apologize for failing to find him earlier, they said.

The Chiba Prefectural Police said they confirmed the remains through dental records and other means.

The skeletal remains, found with coveralls and gloves, were found entangled near the center of a 40-meter-long fishing net that was kept reeled around a drum when workers tried to take it off Thursday at the premises of a used-boat trader in the city of Sanmu, Chiba Prefecture, which bought the net around 2005 from the Niigata-based firm that scrapped Koyama’s boat.

Koyama’s name was released in December 2005 by a group investigating hundreds of missing people thought to have been abducted by North Korean spies, because the disappearance of his navigation records was deemed suspicious.

In 2002, the North admitted abducting Japanese citizens in the 1970s and 1980s and eventually returned some of them to Japan, while claiming that all of the others had already died.