As Seoul pointed the finger at poison- wielding female spies from North of their shared border, police in Kuala Lumpur said they were holding a woman with a Vietnamese passport.
Her arrest came around 24 hours after news broke of the death of Kim Jong Nam, the elder sibling of North Korean leader Kim Jong Un, with reports saying female assassins had sprayed toxins in his face at Kuala Lumpur International Airport.
CCTV images that emerged in Malaysian media, purportedly of one of the suspects, showed an attractive, heavily made-up woman, pictured, wearing a white top with the letters "LOL" emblazoned on the front.
Malaysian police chief Khalid Abu Bakar said 28-year-old Doan Thi Huong was arrested at the airport yesterday morning - two days after the killing. The suspect was "positively identified from the CCTV footage at the airport and was alone at the time of arrest," Khalid said.
Pathologists in the Malaysian capital last night completed an autopsy for clues on how Kim died in a case that has echoes of Soviet-era spycraft.
A black Jaguar sedan bearing the North Korean flag was seen outside Kuala Lumpur Hospital's forensics department.
North Korean government officials objected to the autopsy and requested that the body be released to them right away, but Malaysia rejected the request, sources said.
If confirmed, the assassination - which analysts said could have been ordered over reports he was readying to defect - would be the highest-profile death on Kim Jong Un's watch since the 2013 execution of his uncle, Jang Song Thaek, in a country with a long record of meting out brutal deaths.
South Korea's spy chief Lee Byung Ho said the two women struck on Monday morning as Kim was readying to board a flight to Macau where he has spent many years in exile.
Malaysian police said Kim, a portly 45-year-old, was walking through the departure hall when he was attacked. "He told the receptionist someone had grabbed his face from behind and splashed some liquid on him," Selangor state's criminal investigation chief Fadzil Ahmat was reported as saying by Malaysia's The Star newspaper.
"He asked for help and was immediately sent to the airport's clinic. At this point, he was experiencing a headache and was on the verge of passing out," said Fadzil."At the clinic, the victim experienced a mild seizure.
"He was put into an ambulance and was being taken to the Putrajaya Hospital when he was pronounced dead."
Kim had at one time been set to assume the leadership of his isolated country, but fell out of favor after an embarrassing attempt to get into Japan on a fake passport in 2001.
He had since lived in exile, gaining a reputation as something of a playboy with much of his time spent in Macau, where he was believed to have enjoyed some protection from Chinese security forces.
Cheong Seong Chang of the independent Sejong Institute in Seoul said the assassination was "unthinkable without a direct order or approval from Kim Jong Un himself." His killing was likely motivated by a recent news report that he had sought to defect to the EU, the US or South Korea as far back as in 2012, Cheong said.