The suspect was positively identified from closed-circuit television footage and was alone at the time, he said.
In 2001, he was arrested at Tokyo's Narita Airport after trying to enter Japan on a forged passport from the Dominican Republic.
But the government of South Korea has said it is certain it is him.
"We should take this as an action that reflects Jong Un's paranoia", Lee said. The women, believed to be North Korean agents, then escaped in a taxi, South Korean broadcaster TV Chosun reports.
North Korean officials apparently spent hours trying to convince Malaysia not to conduct an autopsy on Kim Jong-nam, the estranged half-brother of its leader Kim Jong-un. Many media outlets wrongly reported that he was fed to hungry dogs, as punishment for his "betrayal" of the ruling family.
South Korean intelligence officials claimed the regime had been planning his assassination for five years, but did not explain why they thought that was the case. However, National Intelligence Service (NIS) soon appeared to backtrack from the report, saying that Hyon might still be alive.
Other reports have indicated a needle may have also been used.More news: Ultra Street Fighter II to Receive First-Person Game Mode
North Korean defector and well-known dissident Park Sang-hak was also targeted by a Pyongyang-linked hitman.
North Korea, with its secretive and idiosyncratic leadership, is often the subject of dramatic tales that turn out to be exaggerated or flat-out wrong.
One of the two women who authorities said poisoned the playboy half-brother of North Korean leader Kim Jong Un was detained Wednesday in a Malaysian airport. On a more mundane level, it has never been confirmed if Kim Jong Un has children (he is believed to have at least one daughter), what his age is (probably 32 or 33) or many other basic biographical details. Since assuming total control of North Korea, Jong Un has ruthlessly hunted down anyone he perceives as a threat, executing a number of senior officials, including his own 67-year-old uncle. In addition, some North Korea watchers say that the dismissal of the regime's spy agency chief this month may have been related to the death of Kim Jong-nam.
He died on the way to hospital in an ambulance.
"Investigation is in progress and a postmortem examination request has been made to ascertain the cause of death", an earlier statement said. Jang, as the vice chairman of the power National Defense Commission, had been a virtual "number two" to Kim and was close to China, North Korea's longtime benefactor.
Lawmakers briefed by the NIS said Kim Jong Nam sent his younger brother a letter in April 2012, begging for his life and the lives of his family members after a failed assassination attempt. She has a position in a propaganda and agitation department and is known as Kim Jong Un's gatekeeper, Gause said.
After going into exile, Kim repeatedly advocated Chinese-style economic reform in North Korea while publicly opposing the dynastic transfer of power.