Security officials make preparations Tuesday at the Intermediate People’s Court, where disgraced politician Bo Xilai will soon go on trial in Jinan, in China’s Shandong province. Once one of China’s highest-flying politicians, Bo will find himself in a criminal dock Thursday on trial for bribery and abuse of power in the country’s highest-profile prosecution in decades. (Mark Ralston/AFP/Getty Images)

As the closely watched trial of disgraced Communist Party leader Bo Xilai approaches, family members and characters who have stood at the periphery have begun to emerge.

Bo’s son in the United States broke his long silence on his parents’ cases Monday, criticizing the government’s treatment of his father and mother. The family of the British businessman whom Bo’s wife was convicted of murdering is negotiating for financial compensation for his death. And a top forensic scientist who last year cast doubt on evidence cited by authorities in that case resigned in protest against China’s justice system, saying evidence in many cases is routinely disregarded or manipulated.

The increased action in the case comes on the heels of an announcement Sunday that Bo’s trial will begin Thursday, after more than a year of waiting. For much of the interim, the onetime regional party chief has been at the center of scandal, political maneuvering and negotiations within the party. His ouster triggered one of the party’s biggest crises in recent decades and exposed divisions among its leaders. Because of the danger those rifts pose to the party, the outcome of Bo’s trial is believed by many analysts and officials in the party to have already been decided.

Bo’s son, Bo Guagua, said he fears that threats about his welfare might have been used in party leaders’ negotiations with his father, according to a written statement he released Monday to the New York Times.

“[I]f my well-being has been bartered for my father’s acquiescence or my mother’s further cooperation, then the verdict will clearly carry no moral weight,” said the son, a student at Columbia Law School in New York. “I hope that in my father’s upcoming trial, he is granted the opportunity to answer his critics and defend himself without constraints of any kind.”

He also said that he has been denied contact with his parents for the past 18 months, and he spoke in support of his mother, Gu Kailai, who was convicted last year in the poisoning death of British businessman Neil Heywood.

According to a Chinese lawyer representing some members of the Heywood family, they have reached a preliminary agreement with Gu family representatives. He Zhengsheng said in a statement on Sina Weibo, the Chinese equivalent of Twitter, that the government had been facilitating the negotiations, but he did not disclose the financial amounts involved.

Because of the politically charged nature of the case, many legal experts in China and abroad believe Thursday’s proceedings will be for show.

The forensic scientist who resigned this week, Wang Xuemei, had previously criticized the authorities’ investigation of Bo’s wife and the evidence cited in her murder trial. In a video explaining her resignation, Wang avoided mention of Bo’s case but timed its release online Sunday within hours of the government’s announcement of Bo’s court date.

In the video, Wang said she was quitting her job as a forensic expert for the government’s top prosecutor’s office, as well as her vice chairmanship of the Chinese Forensic Medicine Association. She called evidence being presented by the forensic community in courts “ridiculous” and “irresponsible.”

Last year, after the murder trial of Bo’s wife, Wang was the only senior forensic official who criticized the government’s evidence. She said that if Heywood had been killed by cyanide as authorities had said, forensic scientists would have been able to tell quickly from discoloration on the body. Instead, Heywood’s death was initially passed off as alcohol-related.

Wang said recent events — including a case involving a college student who died in a Beijing subway station — had helped her realize that even after 30 years in the field, she had little hope for reform in the justice system.

“Even if I gave my life, I could not rectify the cases which are being unjustly and immorally tried,” she said. “My only option is to quit.”

Li Qi contributed to this report.