An ethnic Korean from China suspected of killing two people and stabbing two others in Siheung, Gyeonggi Province, has told investigators he killed two brothers after they failed to pay him back the money they borrowed 12 years ago.

Charged with murder and attempted murder, the suspect, Cha Cheol-nam, was quoted as saying during questioning while under arrest from Monday night until early Tuesday that the brothers of Chinese nationality had owed him 30 million won, or around 22-thousand U.S. dollars.

Investigators believe Cha killed the older brother around 4 p.m. Saturday after inviting him to his residence, then killed the younger brother about an hour later during a visit to the brothers’ home.

The three men are believed to have known each other since Cha arrived in South Korea in 2012.

Investigators say Cha also told them he stabbed a woman in her 60s, the owner of a convenience store, for badmouthing him, and his landlord in his 70s for having ignored him.

The police are expected to file for a pretrial detention warrant after investigating further.