What killed North Korean ruler Kim Jong Un’s half brother?

North Korea warned Saturday the USA will “pay dearly” if it puts Pyongyang on a terror list over the killing of its leader’s half-brother, as a suspect in the murder claimed he was the victim of a conspiracy.

North Korea is likely to revoke Malaysia’s visa-free travel status in a tit-for-tat move following Malaysia’s decision to impose a new visa application process for North Korean visitors, say experts.

Malaysia’s attorney-general told Reuters on Thursday he was being released due to insufficient evidence.

They have not said why they want to question Kim Uk Il, but believe he is still in Malaysia.

“Therefore this is strong indication that the cause of death is a heart attack”, he said.

The security camera footage, which has been released in the media, showed the two women approaching Jong Nam at the airport departure hall and rubbing a cloth over his face.

As the brother-in-law of Kim Jong-un, he had been living in exile for several years and had begged the North Korean leader to spare his life after a previous assassination attempt. If found guilty, they could be hanged.

Since the poison attack, Pyongyang has also argued that Malaysia’s probe into the case is not impartial and that the country is “in collusion” with forces “hostile” to North Korea.

North Korea, which has not acknowledged the dead man’s identity, has vehemently protested the investigation, saying Malaysia is in cahoots with its enemies.

The new visa requirements might also slow down trade deals between the two countries, but the impact on economic and bilateral relations will be minimal, the experts said.

The diplomatic spat erupted last month when Malaysian police rejected North Korean diplomats’ demands to hand over Kim’s body.

The women have told diplomats from their home countries that they thought they were participating in a prank for reality television.

“We will act firmly to guarantee the safety of the people”. Four of them are known to have left Malaysia. The autopsy is especially sensitive because North Korea had asked Malaysia not to perform one, but authorities said they had to under the law.

Meanwhile, a North Korean chemist deported from Malaysia accused police of threatening to kill his family unless he confessed to Kim’s killing.

On Feb. 20 Malaysia recalled its ambassador from Pyongyang.

North Korea has denied any role and accused Malaysia of bias.

It has provided a channel between Pyongyang and the wider world in recent years, with Kuala Lumpur serving as a discreet meeting place for talks between the regime and the United States.

“Vietnam’s embassy in Malaysia will continue to implement citizen protection measures within their permitted rights to ensure proceedings are fair and objective”, the statement said, adding that the embassy was finding appropriate lawyers for her.