Kim Jong Nam

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Speaking to reporters, Malaysian Inspector-General of Police Khalid Abu Bakar said police had also formally requested an interview with the North Korean embassy'ssecond secretary, who is wanted for questioning.

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. 

Kim Jong Nam, the older half-brother of the North Korean leader, was known to spend a significant amount of his time outside the country and had spoken out publicly against his family's dynastic control of the isolated state.

In a statement, Malaysian police said the dead man, aged 46, held a passport under the name Kim Chol.

Kim Jong Nam has been caught in the past using forged travel documents.

Police official Fadzil Ahmat said the cause of Mr Kim's death was not yet known, and a post mortem would be carried out on the body.