Kim Jong Nam died shortly after he was sprayed with a chemical at Kuala Lumpur Airport last week.
Police have identified four suspects, all men between the ages of 33 and 57, but say they have already left Malaysia.
A North Korean man, an Indonesian woman, and a woman carrying Vietnamese travel documents have been arrested over the death, while a Malaysian man has been detained.
Photo: AFP Kim Jong Nam died after he was sprayed with a chemical at Kuala Lumpur Airport.
