KUALA LUMPUR, Malaysia (AP) — The Latest on the investigation into the assassination of Kim Jong Nam, the estranged half brother of North Korea's leader, in Malaysia (all times local):

6:15 p.m.

A North Korean envoy says a heart attack likely killed Kim Jong Nam, not VX nerve agent as a Malaysia autopsy showed.

Ri Tong Il, the former North Korean deputy ambassador to the United Nations, told reporters Thursday that the victim took medication for heart disease, diabetes and high blood pressure.

He referred to the victim as Kim Chol — the name on the diplomatic passport the victim was carrying. But authorities in Malaysia have said he is Kim Jong Nam, the estranged half brother of North Korea's ruler.

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5:50 p.m.

A high-level defector says he's certain North Korean leader Kim Jong Un was behind Kim Jong Nam's death.

Thae Yong Ho told reporters from Hong Kong-based Phoenix TV that it was unthinkable that Kim Jong Un would not have approved of the high-profile assassination of his half brother.

In the report broadcast Thursday from Seoul, Thae says "North Korea is a society ruled in terror. For a big decision like killing Kim Jong Nam, no one could make a decision like that except Kim Jong Un."

Thae was the former deputy head of the North Korean Embassy in London until last year, when he fled to South Korea, becoming the most senior diplomat to switch sides.

He added that he was "not afraid of terrifying threats (from North Korea). I have to be in public."

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12:15 p.m.

Malaysia's attorney general says a North Korean man will be released and deported because of lack of evidence connecting him to the nerve agent attack on Kim Jong Nam, the estranged half brother of the North Korean ruler.

Attorney General Mohamad Apandi Ali said Thursday that 45-year-old Ri Jong Chol will be released Friday. Malaysia has not described his alleged role in the killing.

He was arrested on Feb. 17, four days after Kim was attacked at Kuala Lumpur's airport.