Idris was one of a number of witnesses to recount the Kim Jong-nam's final moments as the trial began in Malaysia.
North Korea has been developing nuclear-tipped missiles capable of reaching the United States but Pyongyang and Washington both say they want a diplomatic solution.
John Park, the Korea working group director at the Kennedy School of Government at Harvard University, shed further light on the messages Chung was reportedly bringing to Washington.
The apparent offer of talks, not yet publicly confirmed by North Korea, is a tantalizing one for the White House-offering a possible off-ramp from the road to a bloody war. It appears that his objective is two-fold, and his dangling the carrot of "denuclearization" is merely a ruse that he will quickly pull back as soon as his demands are met. Recall his stated belief that his nuclear arsenal is his "treasured sword". "May be false hope, but the US is ready to go hard in either direction", he tweeted.
South Korean officials met North Korean leader Kim Jong Un on Monday in the first such encounter of its kind and said he had expressed his willingness to denuclearise if his country's security is assured. The Koreas hope to open up the Six Party Talks as a mechanism to take the discussion beyond the two governments.
The White House responds with cautious optimism to North Korea's reported openness to hold "candid talks" with the United States, with Pyongyang's nuclear weapons and missile testing programs ostensibly on hold while engaged in negotiations? The North sees these drills and the permanent bases in South Korea, Japan and the Philippines as a provocation - as the infrastructure for an all-out assault on North Korea.
"The Sept. 19, 2005, joint declaration [from the six-party talks] is a failed model", Moon was quoted as saying by Yoo. There's no leverage at the moment for South Korea. Trump himself promised 'fire and fury' on the North, threatened war and said that an 'armada' was on its way to pummel North Korea.
The president's comments came after South Korea said Tuesday the North is willing to start talks with the United States about giving up its nuclear weapons. The high-level South Korean delegation that visited Pyongyang this week was the first to meet Kim since he took power after his dictator father's death in late 2011.
North Korean leader Kim Jong-Un.
Hong reportedly told Moon there could be a huge national catastrophe if the inter-Korean summit turns out to have been the North's scheme to buy time.
Kim Jong Un knows that the only thing guaranteeing his regime's survival is his nuclear weapons - and that the only thing guaranteeing his destruction is using them.
The two sides have also agreed to hold talks between Kim and South Korean President Moon Jae-in in late April in the truce village of Panmunjom.
Although Trump's response was positive, his administration followed it up with another sharp rebuke when it declared that it had formally concluded that Kim's regime had last year murdered his half-brother in a Malaysian airport with the banned VX nerve agent.
"The ultimate goal that we should achieve is denuclearization", he said.
Why is North Korea acting now?"That's the part that we're waiting to potentially hear about, if that becomes a basis that's sufficient for the US side to move forward in terms of talks".
Seoul officials see the talks as the starting point of President Moon Jae-in's initiative to denuclearize and build lasting peace on the peninsula, beginning with a freeze in the North's nuclear program and ending in its complete abolishment.