A senior North Korean official has been identified as a suspect in his death
Security has been increased following an attempted break-in at the mortuary where Kim Jong-Nam's body is being held.
Police have confirmed the hospital building was targeted last week in an attempt to get to the corpse, which has been undergoing a post-mortem examination.
Malaysian police chief Khalid Abu Bakar told the Malay Mail that they have now had to "take precautions", and "will not allow anyone to tamper with the mortuary".
Kim Jong-Nam's cause of death is still unknown, and further tests are under way.
Meanwhile, Malaysian police have identified a senior official in the North Korean embassy as a suspect in the murder.
A second suspect, Kim Uk Il, who is linked to the North Korean airline Air Koryo, has also been called in for questioning over the killing of Kim Jong-Un's half-brother at Kuala Lumpur International Airport last week.
Mr Bakar said both suspects were still in Malaysia and had been summoned for questioning.
He said the diplomat, identified as Hyon Kwang Song, was a second secretary at the embassy and added that four other suspects who fled Malaysia on February 14th - the day after the attack - are thought to have arrived in the North Korean capital Pyongyang.
"We have written to the ambassador to allow us to interview both of them," he said.
"We hope that the Korean embassy will co-operate with us and allow us to interview them quickly. If not we will compel them to come to us."
Mr Kim was attacked at the airport on February 13th as he prepared to board a flight to Macau.
Mr Bakar said two female suspects, who are in custody, were trained to wipe an unidentified toxin on Mr Kim's face, then wash their hands.
He said the toxin was placed on the Indonesian and Vietnamese women's hands by a North Korean suspect, who is in custody.
"We strongly believe it is a planned thing and that they have been trained to do that. This is not just like shooting a movie," he said.
Authorities are seeking eight others, including the two announced on Wednesday.
Tensions between North Korea and Malaysia have escalated since Mr Kim's death, with a row building over custody of the victim's body and Pyongyang's criticism over the handling of the investigation.
Malaysia recalled its ambassador from Pyongyang earlier this week after the North Korean diplomat in Kuala Lumpur cast doubt about the fairness of the police investigation.
No family member has come forward to claim Mr Kim's body.