Ri Jong Chol, a North Korean arrested in the probe into last week's murder of the half-brother of the isolated state's leader, lived in Malaysia for more than three years without working at the company registered on his employment permit or receiving a salary.

Malaysia's ambassador to Pyongyang says the investigation into the death of the exiled half-brother of North Korea's ruler is being conducted in an impartial manner.

Investigators are looking for four North Korean men who flew out of Malaysia the same day Kim Jong Nam, the North Korean ruler's outcast half brother, apparently was poisoned at an airport in Kuala Lumpur, Malaysian police said Sunday.