By October 2010, looking for business for a new company he had created, Mr. Lee was accompanied to a business meeting by Chinese intelligence officers, who vouched for him, Japan Tobacco was later told by people at the meeting.

Mr. Lee was taken into custody on Monday after arriving at Kennedy International Airport and charged with a single count of retaining classified information. The charge, which carries a maximum sentence of 10 years, related to Mr. Lee’s possession in 2012 of two notebooks that contained the identities of Chinese nationals working for the C.I.A. and other highly classified details. Mr. Lee’s repeated contacts with Chinese intelligence would be of great relevance to the question of whether he may have been recruited by China and played a role in the betrayal of C.I.A. secrets.

During the early years of the investigation into the loss of sources in China, there were disagreements between the C.I.A. and F.B.I. over whether Mr. Lee was the likely source of the breach. Some investigators believed that China might have penetrated the C.I.A.’s covert communications or that sloppy tradecraft by the agency might have exposed operations.

Mr. Lee does not yet appear to have a lawyer, though he was represented by a federal public defender during a court appearance this week. He has not been charged with espionage, and no evidence has publicly emerged linking him directly to the deaths of the C.I.A. sources in China.

The colleague, who was formerly a senior manager with Japan Tobacco and worked closely with Mr. Lee there, said the company had good reason to believe Mr. Lee’s claim that he had been the C.I.A. liaison to the Ministry of State Security, though he declined to give details. He said the company also believed the later report that Mr. Lee was meeting in 2010 with Chinese intelligence, which came as a tip from a Chinese official to a veteran investigator with Japan Tobacco, a former Hong Kong police investigator who had handled many tobacco cases.

Mr. Lee’s reported false claim that Japan Tobacco investigators were actually working for the C.I.A. alarmed company officials, who thought it would put at risk every company investigator who traveled in China. He said the claim had no basis in fact, and that any perception of an association with any foreign intelligence service was carefully avoided because it would have been dangerous for Japan Tobacco employees in China.

Company officials thought the false C.I.A. claim was an act of revenge for Mr. Lee’s firing. For months, the company banned all travel to the rest of China by Hong Kong-based investigators, said the former colleague.