Video footage presented in court showed Vietnamese suspect Doan Thi Huong walking in the airport with a man wearing a baseball cap.
Separately, Indonesian suspect Siti Aisyah was seen meeting with another man also wearing a cap at an airport cafe just before the attack was carried out in a crowded departure terminal of the Kuala Lumpur airport the morning of February 13.
The faces of the men can't be seen clearly. Chief investigating officer Wan Azirul Nizam Che Wan Aziz identified the men as only Mr Y and Mr Chang.
He testified the two men were believed to have smeared VX on the women's hands before the pair smeared the oily substance on Kim Jong Nam's face.
Wan Azirul said the two men are among four people at large whom prosecutors accuse of having the common intention with the two women to murder Kim.
He named the two other at-large suspects as James, the suspected recruiter of Aisyah, and Hanamori, who is nicknamed grandpa or uncle and who is suspected of giving directions to Mr Y.
No further details about those four suspects were disclosed in open court, though police have previously said at least seven North Koreans who have left Malaysia are suspected of involvement.
Huong and Aisyah are the only two suspects detained in the brazen assassination of Kim, an outcast from North Korea's ruling family who lived abroad in virtual exile for years.
Both women have pleaded not guilty to murder charges that carry mandatory death sentences if they are convicted.
Their defense lawyers have said Huong and Aisyah were duped by suspected North Korean agents into believing they were playing a harmless prank for a TV show.
Prosecutors however, contend the women knew they were handling poison.
Security videos presented at the trial yesterday showed the women hurrying off to separate washrooms after the alleged attack on Kim, with their hands held away from their bodies as if to avoid contact.
Experts have testified that VX can be safely removed by careful hand-washing within 15 minutes of exposure.
Aisyah's lawyer, Gooi Soon Seng, has told reporters previously that she was recruited in early January by a North Korean man known just as James to star in what he said were video prank shows.
The lawyer said James had Aisyah go to malls, hotels and airports and rub oil or pepper sauce on strangers which he would film on his phone, and paying Aisyah between USD 100 and USD 200 for each prank.
James later introduced Aisyah to a man called Chang, who said he was the producer of Chinese video prank shows.
On the day of Kim's death, Chang had pointed Kim out to Aisyah as the next target and put the substance in her hand, the lawyer has said.
Police say Chang was actually Hong Song Hac, one of four North Korean suspects who left Malaysia on the day of the killing, while James was Ri Ji U, one of another three North Koreans who hid inside their country's embassy in Kuala Lumpur to avoid questioning.
Those three were later allowed to fly home in exchange for nine Malaysians being allowed to leave Pyongyang in a deal easing a diplomatic standoff that brought relations between the two countries to historic lows.
Malaysia never directly accused North Korea, but South Korea's spy agency has said the attack was part of a five-year plot by North Korean leader Kim Jong Un to kill a brother he reportedly never met. Kim Jong Nam was not thought to be seeking influence over his younger brother but had spoken out publicly against his family's dynastic rule.
The trial will resume on October 24 with a visit to the crime scene at the airport.