It looks like a perfectly staged assassination, straight out of the pages of a spy novel: Kim Jong-nam, the estranged, exiled half-brother of North Korean leader Kim Jong-un, falls ill at a Malaysian airport, complains of being sprayed with some sort of chemical and drops dead.

But, as with many things about the alleged motives of cloistered North Korea, the unknowns currently far outweigh the certainties.

A look at what officials are trying to piece together as they work to reconstruct one of the most audacious, mysterious assassinations in recent Asian history:

Why now?

This is the big one: Motive.

Kim Jong-nam, a jovial, overweight gambler and playboy, had embarrassed Pyongyang before - he tried to sneak into Tokyo Disney; he criticised his half brother - but he's been generally seen more as an annoyance than an existential threat to North Korea's stability.

Why would Kim Jong-un go through the massive logistical trouble - and potential embarrassment - of staging the risky assassination of a blood relation on foreign soil?

Without elaborating, South Korea's spy service has told lawmakers that the North had been trying to kill Kim Jong-nam for five years. Spy officials offered a single, shaky motive for the death: Kim Jong-un's “paranoia” over his estranged half brother.

But the South's National Intelligence Service has a long history of botching intelligence on North Korea and has long sought to portray the North's leadership as mentally unstable.

Some in Seoul wonder if Kim Jong-un might have become enraged when a South Korean newspaper reported last week that Kim Jong-nam tried to defect to the South in 2012. South Korea's spy service denied this, but it's still an open question: Could public speculation that a member of the exalted Kim dynasty wanted to flee to the hated South have pushed Kim Jong-un to order his half brother's assassination?

Why the airport in Malaysia?

There would seem to be easier, less public places to kill such a high-profile target.

A possible explanation might be found in another nugget provided by South Korea's spy agency: China had long protected Kim Jong-nam and his family in their home base of Macau. Analysts have seen Beijing as looking to Kim Jong-nam as a potential leader should North Korea's regime collapse.

With security, presumably overseen by China, tight in Macau, could there have been a security gap in Malaysia that offered North Korean assassins an opportunity they couldn't have gotten elsewhere?

Who are the mystery women?

The details of the attack itself are a tangled mess as of now.

Kim told medical workers that he'd been sprayed with a chemical, which brings to mind past attacks with poison-tipped pens linked to North Korean assassins.

South Korea's spy agency says two women believed to be North Korean agents attacked Kim. They then reportedly fled. Japanese media quoted the government in Tokyo as saying those women may now be dead. None of this has been confirmed yet.

Still, finding out who these women are and who hired them could go a long way to unlocking the mystery.

What next?

North Korea has said nothing officially about the death, but that's not unusual. The country's propaganda specialists are masters at reporting only details that lionise the Kim family as paragons of virtue. This clearly doesn't do that.

China may be angry at the killing of a close North Korean contact, so there could be some sort of reaction, possibly back-channel, from Beijing.

Inside the daily life in North Korea Show all 19 1 /19 Inside the daily life in North Korea Inside the daily life in North Korea People reading a newspaper at the metro station Inside the daily life in North Korea Thoughts of the leaders on the tram. They have about a dozen of these on every tram, all with different thoughts Inside the daily life in North Korea Young people training for a big upcoming festival Inside the daily life in North Korea People at the Pyongyang's annual marathon Inside the daily life in North Korea Many stars on one of the trolleys in Pyongyang Inside the daily life in North Korea An intimidating poster in a primary school in North Korea. Inside the daily life in North Korea Solar panels installed on a street lamp. Inside the daily life in North Korea A poster on the window next to one of the venues we visited in Pyongyang Inside the daily life in North Korea Kids playing football next to the Arch of Triumph. After a while tourists were allowed to join, so some of us did Inside the daily life in North Korea Class in an educational center in Pyongyang (where people over 17 years old can attend any classes they choose after school, for free) Inside the daily life in North Korea People waving at me during the Pyongyang marathon Inside the daily life in North Korea People having a great time dancing at a public park Inside the daily life in North Korea A metro driver in a metro station in Pyongyang Inside the daily life in North Korea Fireworks to mark the birthday of the Eternal President Kim Il Sung on our last night in Pyongyang Inside the daily life in North Korea My wonderful tour guide at a public park Inside the daily life in North Korea One of the parks in Pyongyang Inside the daily life in North Korea A person rowing some boats for the day at a river in Pyongyang Inside the daily life in North Korea The National War Museum Inside the daily life in North Korea Public park in Pyongyang

But a more concrete punishment could come from Washington.

Cheong Seong-chang, a South Korean analyst, said the assassination might convince the US Congress to re-list North Korea as a state sponsor of terrorism, further isolating the already widely shunned country.