The U.N. special rapporteur on North Korea said Monday the recent murder in Malaysia of Kim Jong Nam, the estranged half-brother of North Korea's leader, could amount to an extrajudicial killing, which would open the door to international investigation.

"Should the investigation confirm the involvement of state actors, Mr. Kim would be a victim of an extrajudicial killing and measures would need to be taken to assign responsibilities," Tomas Ojea Quintana said during a session of the U.N. Human Rights Council.

Malaysian authorities suspect North Korea orchestrated the assassination of Kim Jong Un's half-brother, who is known to have criticized the country's hereditary succession, at Kuala Lumpur International Airport on Feb. 13, using the highly toxic nerve agent VX. North Korea claims the man died from a heart attack.