One by one, the pieces of the mysterious death of Mr Kim Jong Nam appear to be falling into place.
Malaysian police say an extremely toxic substance used in chemical warfare killed the half-brother of North Korean leader Kim Jong Un at the departure hall of Kuala Lumpur International Airport.
It is known as VX, the deadliest of all known chemical warfare agents.
A tiny drop on your skin can kill within minutes. Like any other nerve agents, VX works faster once it touches any mucous membrane such as those found in the human eye.
In this case, traces of VX were found on swabs taken from the victim's eye.
But if VX is so deadly, how did the two suspects survive the attack? After all, Malaysian police said the duo used their bare hands to wipe his face with a toxic liquid.
One possibility could be that VX was delivered in "binary" form, meaning two relatively harmless compounds were combined at the last moment to create the lethal nerve agent.
This explains why the Feb 13 attack involved two assailants, some experts have said .
"They could have wiped two or more precursors in his face," nonproliferation expert Melissa Hanham told The Guardian. The method was developed by the US Army to enable safer handling and storage of chemical weapons.
Also, as VX is extremely stable and does not evaporate quickly, it remains intact on a cloth or some other surface until it touches human skin, defence expert Bruce Bennett explains in an article on BBC News.
CCTV footage leaked earlier this week showed one of the two female suspects reaching over Mr Kim Jong Nam's head from behind and covering his face with a cloth.
After the attack, Mr Kim Jong Nam was visibly well enough to approach airport staff for help and explain the attack to them. He also walked unaided to a clinic located one level below the departure hall.
But at the clinic, he suffered a seizure, one of the many symptoms of VX poisoning.
He died on the way to the hospital.
"The cause of death of Kim Chol is VX nerve gas," Malaysian police chief Khalid Abu Bakar said on Friday (Feb 24), refering to the name on the victim's diplomatic passport, which he used to enter the country.
He also revealed that one of the two female suspects has shown effects of VX exposure, including vomiting.
"We will investigate how the VX came into the country," he told reporters.
Mr Bennett told BBC because the quantity required to kill is extraordinarily small, the nerve agent could have been smuggled into Malaysia "in a cartridge in a pen or some such thing".
Security expert Rohan Gunaratna told AFP it would not have been difficult to get VX into Malaysia in a diplomatic pouch, which are not subject to regular customs checks.
North Korea had previously used the pouches "to smuggle items including contraband and items that would be subjected to scrutiny if regular travel channels were used", said Mr Gunaratna, the head of the Singapore-based International Centre for Political Violence and Terrorism Research.
Malaysian police have identified at least seven North Koreans they suspect planned and help carry out the attack on Mr Kim Jong Nam. One of the suspects is a Second Secretary at the North Korean embassy.
North Korea is believed to have the world's third-largest stockpile of chemical weapons after the United States and Russia, according to the Nuclear Threat Initiative website.
Mr Ankit Panda, writing in The Diplomat, said the use of VX adds to the growing list of evidence pointing to the fact that Mr Kim Jong Nam's killing was a state-sanctioned assassination, despite North Korean denials.
"It's unclear if the Kim Jong Nam assassination was meant to serve the secondary purpose of signaling to the world that North Korea definitively possesses the capability to synthesise VX," he added in the piece published on Friday (Feb 24).
But the incident has clearly illustrated the dangers to public health if such chemical weapons fall into the wrong hands. VX is classified as a Weapon of Mass Destruction (WMD) by the United Nations.
The use of VX at a busy international airport also showed a "complete disregard for international norms or the safety of bystanders", The Guardian's World affairs editor Julian Borger wrote.
The US government's Centre for Disease Control and Prevention warns: "Because it evaporates so slowly, VX can be a long-term threat as well as a short-term threat. Surfaces contaminated with VX should therefore be considered a long-term hazard."
In a statement issued on Friday night, the Malaysia Airports says the staff and personnel who attended to the victim are in good health.
Non-proliferation experts and North Korea watchers are calling for more attention to be paid to the North's chemical weapons programme.
Mr Cheong Seong Chang of Sejong Institute told Wall Street Journal: "Such a threat is even more serious and realistic than that of nuclear weapons or ballistic missiles."
Ms Duyeon Kim, a non-resident associate in the Nuclear Policy Programme and Asia Programme at the Carnegie Endowment for International Peace, tweeted: "NK biochem programme scarier & more serious than their nukes but no one really paying attention.
"We are too focused on nukes, including myself."