Police have put five North Koreans in the frame for the killing and have said they are seeking three more for questioning.
Of those wanted for questioning, one is attached to the embassy and one is on the staff of a North Korean airline, the police chief told reporters.
"We have written to the ambassador to allow us to interview both of them. We hope that the Korean embassy will cooperate with us and allow us to interview them quickly. If not we will compel them to come to us," Khalid said.