The details of the attack: Kim Jong-nam was at the Kuala Lumpur International Airport getting ready to fly to Macau, China, when he reportedlysaid someone grabbed or held his face from behind and attacked him, a Malaysian police official told Reuters.
Kim Jong-Nam told staff at Kuala Lumpur International Airport that he felt "dizzy" after an unknown person had wiped his face with an unidentified object, reports the New Straits Times.
Although there was scant evidence that Kim Jong Nam was plotting against the North Korean leader, he provided an alternative for North Koreans who would want to depose his brother.
Kim Jong-Nam was the son of late North Korean leader Kim Jong-Il. He shuttled between Beijing and Macau, where his two wives lived, until 2011, when his father died, according to Chosun.
The only holiday that is more important is the "Day of the Sun", which marks the birthday of Kim Jong Un's grandfather, North Korea's founder and "eternal president" Kim Il Sung. He said he wanted to visit the Tokyo Disneyland.
Daily Mail and The Sun UK highlighted reports that Jong Nam was a "playboy".
Ko and Kim Jong-il had another son, Kim Jong-chol, who was seen at an Eric Clapton concert in London in 2015.
The Star also reported of freaky speculation, with an an online news agency called the Democratic People's Republic of Korea, a satire site, claiming that Jong Nam had died from "unsanitary food practices" by Malaysians. They are suspected to have been North Korean agents.
A North Korean spy jailed by South Korea in 2012 was reported to have admitted trying to organise a hit-and-run accident targeting him.
Jong-nam had been outspoken regarding his family's control over the country.
The North Koreans have been implicated in at least one other poison needle attack, in 2011, when a South Korean pastor and activist died mysteriously in China.
But Mr Foster-Carter speculates the kill order may not have come from Kim Jong-un.
"The timing is weird because this guy had been sort of vague trouble for Kim Jong-un in terms of some of the stuff that he said, but it was four or five years ago", added Mr Foster-Carter.
In 2013, Kim Jong-un ordered the execution of their uncle and mentor, Chang Song-thaek, previously the second most powerful man in the country - and to whom Kim Jong-nam was particularly close. Officials were not immediately available for comment or direct confirmation of the elder Kim's death.
Experts see the Kim's assassination, if confirmed, as a "terror" act that could bolster the move in the U.S.to relist the North as a state sponsor of terrorism.