A man in his 40s has confessed to a 2008 robbery and murder case in Siheung, Gyeonggi Province, local police said Wednesday.

The suspect told investigators that he had been the one who stabbed a supermarket owner on Dec. 9, 2008 in Siheung, 26 kilometers southwest of Seoul. "I stabbed him. I'm sorry," was what he said, according to Siheung Police Station.

The suspect has not elaborated on his motive for the crime.

Authorities have been questioning the suspect since apprehending him at around 8 p.m. Sunday from his home in South Gyeongsang Province. Siheung Police said it received a decisive tip-off related to the case in February.

The unresolved robbery-murder case had stumped local police for years, as they lacked evidence to identify a suspect. A mask-wearing assailant thought to be in his 30s had entered the supermarket at around 4 a.m. and demanded money from the owner, stabbing him after a scuffle.

The crime was captured by the store's surveillance camera, but the authorities had never managed to track down the suspect.

The case was reopened in 2017, but it closed again after six months with no results.

The suspect attended his warrant application hearing at the Ansan Branch of the Suwon District Court Wednesday morning, without responding to any questions by the media.