According to the Journal´s source there was a "nexus" between Kim Jong Nam and the CIA, but the paper said many details of his connection with the intelligence agency were unclear.
Kim Jong Nam, who was once seen as heir apparent to the North´s leadership, died after having his face smeared with the outlawed VX nerve agent as he waited at Kuala Lumpur airport.
CNN national security analyst Sam Vinograd, who served on President Barack Obama's National Security Council, ripped President Donald Trump for his reaction to a report about the Central Intelligence Agency and North Korea.
Meanwhile, his former privileged position in the family's hereditary dynasty was overtaken by his youngest half-brother, Kim Jong-un, who assumed power shortly after their father's death in December 2011. US and South Korean officials have blamed the attack on North Korea, which it denies. The half brother was estranged from the Kim family after he was caught trying to travel to Japan with false passports in 2001.
A man believed to be Kim Jong-Nam is surrounded by journalists upon his arrival at Beijing's capital airport, in February 2007. The newspaper said that an unnamed "person knowledgeable about the matter" had provided information about the case. Nick Schifrin talks to The Washington Post's Anna Fifield, author of "The Great Successor: The Divinely Perfect Destiny of Brilliant Comrade Kim Jong Un". They were arrested days later and charged with murder.
Doan Thi Huong, a woman from Vietnam, pleaded guilty to a lesser charge of "causing injury" and she was released from prison last month.
After exchanging insults and war-like rhetoric with Kim early in his presidency, Trump in the past year has repeatedly praised him.
It's extremely hard to verify information about North Korea's ruling family.
A human rights group said Tuesday it has identified hundreds of spots where witnesses claim North Korea carried out public executions and extrajudicial state killings as part of an arbitrary and aggressive use of the death penalty that is meant to intimidate its citizens.
Trump, speaking a day before the one-year anniversary of their landmark Singapore summit, did not rule out another meeting with Kim.