BEIJING — A French architect who has an apparent connection to a political scandal in China has agreed to return to that country after Cambodia released him from custody at Beijing’s request, Cambodian officials said Wednesday.

Information Minister Khieu Kanharith told reporters in Phnom Penh, the Cambodian capital, that the architect, Patrick Devillers, had voluntarily boarded a plane for Shanghai on Tuesday night.

He said Mr. Devillers, who was arrested on June 13 but never charged with any crime, had agreed to cooperate with the Chinese authorities investigating the death of a British businessman.

Cambodian officials said Mr. Devillers’s release, like the arrest, was made at Beijing’s request. Mr. Devillers has been linked to the disgraced Chinese politician Bo Xilai and to Mr. Bo’s wife, Gu Kailai, who has been implicated in the murder of the businessman, Neil Heywood. His body was found last November by the police in a hotel room in Chongqing.

The scandal led to the downfall of Mr. Bo, the former party chief of Chongqing, who was stripped of his post after being accused of disciplinary violations. The French Embassy in Beijing had no immediate comment.

Mr. Devillers’s connection to the couple dates to the 1990s, when he provided architectural services to Mr. Bo during his tenure as mayor of the port city of Dalian. In 2000, Mr. Devillers joined Ms. Gu in a British business venture. At one point the two shared an address in the British city of Bournemouth.

For the past six years, Mr. Devillers, 51, has lived what appeared to be a quiet life in Cambodia with a local woman and their young child. Friends say his previous marriage to a Chinese woman from Dalian ended in divorce. It is unclear why Mr. Devillers would voluntarily return to China, given past statements suggesting that he had no interest in getting involved in the scandal. He has denied any wrongdoing.

One possible explanation is that the Chinese authorities have agreed to grant him immunity from prosecution in exchange for his testimony at a trial of Ms. Gu for Mr. Heywood’s murder.

Information Minister Khieu Kanharith of Cambodia was quoted by Reuters and The Associated Press as saying that Mr. Devillers returned to China to act as a “witness.”

Though he was arrested at the behest of the Chinese, Cambodian officials, responding to protests from French diplomats, later insisted they would not send Mr. Devillers to China without proof of wrongdoing.

Beijing maintains significant leverage over Cambodia through generous aid, but the country’s elite is also closely tied to France, its former colonial power. The arrest heightened diplomatic tensions between Beijing and Paris.

The Chinese state news media, which in recent months has imposed a virtual blackout on news related to the scandal involving Mr. Bo and his wife, made no mention of Mr. Devillers’s release. The announcement that Mr. Devillers had left Cambodia for China came a week after the Chinese foreign minister, Yang Jiechi, met with his French counterpart in Beijing.