Malaysian detectives probing the assassination of Kim Jong-Nam admitted Thursday that they cannot force a wanted North Korean diplomat to answer their questions.
The investigation into the airport killing of the half-brother of North Korean leader Kim Jong-Un has narrowed in on eight of his countrymen, who police suspect were involved in the plot to poison him.
But Malaysia's top policeman acknowledged Thursday that unless Hyon Kwang Song, second secretary at the North Korean mission, volunteers himself, they will be unable to speak to him.
"We will adhere to the rules of immunity," Khalid Abu Bakar said. "We cannot go inside the embassy." But he added: "If you have nothing to hide, you should not be afraid to co-operate, you should co-operate."
The exiled Jong-Nam was attacked on February 13 at Kuala Lumpur International Airport as he readied to board a plane to Macau.
Leaked CCTV footage showed two women approaching the heavy-set 45-year old and appearing to push something in his face.
He is then seen seeking help from staff who ultimately call an ambulance.
Police say he suffered a seizure and was dead before he arrived at hospital.
Detectives are holding three people - women from Indonesia and Vietnam, and a North Korean man - but would like to speak to seven others, including diplomat Hyon and an airline employee called Kim Uk Il.
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They said earlier this week they would "compel" the two men to "come to us".
Khalid declined to say if he believed Kim and Hyon were in the embassy but said police would apply for a warrant for Kim's arrest if he did not surrender.
Four of the men on the wanted list fled the country on the day of the murder and returned to Pyongyang, police say.
Khalid added Kuala Lumpur has asked Interpol to put out a notice on the four fugitives overseas.
Authorities have said Jong-Nam's body cannot be released unless his family provide DNA samples, but Khalid denied reports his officers will travel to Macau, where the dead man lived, to collect a sample.
The police chief also hit back at North Korean claims that Malaysia was playing politics with the corpse.
"The police will carry out a fair and just investigation," he said.