Transcript for Fourth arrest announced in murder North Korean leader's brother

Heading overseas now to a bizarre international murder mystery. Malaysian police just announcing a fourth arrest in the shocking murder of the brother of north Korea's leader. ABC's Jennifer Eccleston with the latest twist in that case. Reporter: Tonight, the mystery deepens as North Korea goes on the attack, demanding the immediate release of Kim Jong nam's body -- the older half-brother of dictator Kim Jong un. They are deceiving us. Reporter: The regime claiming the Malaysian government's autopsy is invalid. There's every indication based on North Korea's history that this was a targeted kill. Reporter: A north Korean in custody, joining two alleged female assassins accused of killing Kim Jong nam in an airport. One seen in surveillance images with an "lol" shirt. The other, an Indonesian woman. Her family claims she thought she was part of a candid camera TV show, spraying Kim Jong nam -- along with several other men -- in the face for laughs. Unaware of any potential deadly chemicals inside. Right now, the Malaysians are refusing that demand to turn the body over as they continue to question the suspects in this bizarre case. Tom. Jennifer Eccleston from London tonight. Jennifer, thank you.

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