Lee Bo, 65, was one of five men who work at a publishing house critical of Beijing's ruling elite to disappear in recent months, raising fears
that he'd been detained by mainland Chinese authorities and further stoking concerns over decreasing freedom of speech in the city.
Chinese authorities confirmed
last week that Lee had crossed the border into the neighboring province of Guangdong. His wife informed Hong Kong police on Saturday night that she had met up with him, also passing on a letter purportedly written by him.
Lee's wife, Choi Ka-ping, told Hong Kong police that she met him at a guesthouse in mainland China on Saturday. He was healthy and in good spirits, she said, and was assisting in an investigation as a witness.
Choi did not disclose further details regarding the location of the meeting or the nature of the investigation he was involved in.
The letter, later published by local newspapers, called on police to close his case.
"I have already met with my wife," the letter reads.
"Over here, I am free and safe. My wife told me after she received my phone call she did not intend to call the police. It was others that reported to the police, and incited her to report to the police. After that, she felt used and went to the police station to close the case."
It continues: "I hope the Hong Kong police will not continue to waste police resources on my case, and there's no need to continue investigating. I went to the mainland to cooperate in an investigation voluntarily. Solving a problem takes some time, it involves many of my private and company's internal affairs."
CNN was not able to independently authenticate the letter.
It is similar to another one purportedly written by Lee dated January 3 in which he says he left Hong Kong of his accord and assured he was safe.
The Hong Kong Police however said they would continue to investigate the incident and have requested the Guangdong Public Security Department to assist in arranging a meeting with Lee.
String of disappearances
Lee, a British national, was first reported missing on December 30 and was last seen near his company's warehouse. Days later, his wife contacted police to cancel the report but under Hong Kong law, only the subject of a missing person report can cancel it.
Mighty Current, Lee's publishing house, specializes in books often critical of China's top politicians and also operates a bookstore, Causeway Bay Books.
Last week, one of Lee's associates, Gui Minhai, who had gone missing in Thailand, resurfaced in mainland China, tearfully "confessing"
to a 2003 crime on Chinese TV.
In the video, he says he went to China voluntarily to see his aging mother and to assuage his guilt regarding a hit and run accident.
According to Hong Kong lawmaker Albert Ho, the publishing company has been working on a book detailing Chinese President Xi Jinping's love affairs.
The men's disappearances has sparked angry protests
in Hong Kong and calls for an investigation of how Lee and Gui ended up in mainland China.