North Korea's top envoy in Kuala Lumpur on Monday denounced Malaysia's investigation into the apparent killing of the exiled half brother of North Korea's ruler, calling it politically motivated and demanding a joint probe into the death. The comments from Ambassador Kang Chol came amid rising tensions between North Korea and Malaysia over the death, with Malaysia recalling its ambassador to Pyongyang over what it called "baseless" allegations. Kim Jong Nam, the estranged half brother of North Korean ruler Kim Jong Un, died last week after apparently being poisoned in a Kuala Lumpur airport. Security camera footage obtained by Japanese television appeared to show a careful and deliberate attack in which a woman comes up from behind him and holds something over his mouth. Pyongyang demanded custody of Kim's body and strongly objected to an autopsy. The Malaysians still went ahead; an official with knowledge of the investigation said they conducted a second autopsy because the first was inconclusive, though police denied that. The official spoke on condition of anonymity because he was not authorized to speak to the media. Malaysian authorities say they were simply following procedures, but Kang questioned their motives. "The investigation by the Malaysian police is not for the clarification of the cause of the death and search for the suspect, but it is out of the political aim," Ambassador Kang Chol told reporters Monday. He referred to the dead man as "Kim Chol," the name on the passport found with Kim Jong Nam. Police had "pinned the suspicion on us," Kang said, calling on Malaysia to work with North Korea on a joint investigation. Malaysia Prime Minister Najib Razak told reporters later Monday that he has "absolute confidence" that police and doctors have been "very objective" in their work. Najib said Malaysia had no reason to "paint the North Koreans in a bad light" but added, "We expect them to understand that we apply the rule of law in Malaysia." Kang previously said Malaysia may be "trying to conceal something." On Monday, the Malaysian foreign ministry said it had recalled its ambassador to Pyongyang "for consultations" and had summoned Kang to a meeting, "to seek an explanation on the accusations he made." The statement called Kang's comments "baseless" and said it "takes very seriously any unfounded attempt to tarnish its reputation." Police investigating the killing have so far arrested four people carrying identity documents from North Korea, Malaysia, Indonesia and Vietnam. Those arrested include two women who were allegedly seen approaching Kim on Feb. 13 as he stood at a ticketing kiosk at the budget terminal of the Kuala Lumpur airport. Surveillance video footage, obtained by Fuji TV and often grainy and blurred, seems to show the two women approaching Kim Jong Nam from different directions. One comes up behind him and appears to hold something over his mouth for a few seconds. Then the women turn and calmly walk off in different directions. More footage shows Kim, a long-estranged scion of the family that has ruled North Korea for three generations, walking up to airport workers and security officials, gesturing at his eyes and seemingly asking for help. He then walks alongside as they lead him to the airport clinic. Fuji TV has not revealed how it acquired the video footage, which was taken by a series of security cameras as Kim arrived for a flight to Macau, where he had a home. Kim, in his mid-40s, died shortly after the attack, en route to a hospital after suffering a seizure, Malaysian officials say. Malaysia's deputy national police chief, Noor Rashid Ibrahim, said Sunday that Kim had told airport customer service workers that "two unidentified women had swabbed or had wiped his face with a liquid and that he felt dizzy." — AP