A Hong Kong publisher reported missing last October has appeared on Chinese state TV saying he voluntarily handed himself over to the authorities.
Gui Minhai said he turned himself in after being on the run for 12 years over a drink-driving conviction.
Mr Gui, a Swedish national, is one of five Hong Kong booksellers to go missing recently.
Some in Hong Kong have alleged they are being detained by China because of a book critical of the mainland.
Thousands joined rallies in Hong Kong last week over the disappearances, saying it amounted to an erosion of freedoms.
The Chinese state news agency Xinhua said Mr Gui, 51, was involved in a fatal car accident in the eastern city of Ningbo, in which a female college student was killed. It said he fled while under a suspended two-year jail term.
"I am taking my legal responsibilities, and am willing to accept any punishment," he told CCTV, according to Xinhua.
Public confessions have long been a part of China's criminal law, but experts say many confessions are forced.
Mr Gui was the owner of the Mighty Current publishing house in Hong Kong. He failed to return from a holiday in Thailand in October.
Activists believe he was unlawfully transported to China because of an unpublished book about the private life of the Chinese president.
The five who went missing either work for Mighty Current or a small bookstore it owns called Causeway Bay Books.
The bookshop is known for selling works critical of China which are banned in the mainland.
Mystery disappearances in Hong Kong book world
Gui Minhai: 51, disappeared while staying in Thailand in October 2015. The China-born Swedish national owns the Mighty Current publishing house
Lui Bo: last seen in mainland China, just north of Hong Kong, in October 2015. General manager of Mighty Current
Cheung Jiping: 32, last seen in mainland China in October 2015. Mighty Current's business manager
Lam Wingkei: 60, last seen in Hong Kong in October 2015. Manager of Causeway Bay bookstore
Lee Bo: 65 - also known as Paul Lee - disappeared in Hong Kong in late December 2015. A shareholder in Causeway bookshop and a UK passport holder. Wife withdraws request for police to help find him in early 2016 saying he has been in contact from mainland China
During the recorded interview, Mr Gui also asked the Swedish authorities not to get involved.
"Even though I am a Swedish national, I truly feel that I am still Chinese and my roots are still in China. So I hope that the Swedish side would respect my personal choice, rights and privacy and let me solve my own problems," he said.
A spokeswoman for the Swedish foreign ministry said it was aware of reports but not commenting, and was seeking clarification from China.
Last Sunday, thousands of protesters marched to the offices of Beijing's representative in Hong Kong, chanting "say no to political kidnapping".
The latest to vanish was Lee Bo, in late December - Mr Lee raised the alarm after four of his associates went missing in October.
Hong Kong authorities have said they are conducting a "thorough" investigation into the disappearance of the five men.
Under the "one country, two systems" principle, Hong Kong is supposed to enjoy high degrees of autonomy from China.
Albert Chan, a politician with the pro-democracy People Power Party, told the BBC last week he believed the case was "the first time there has been such a clear violation of Hong Kong's law".