For months, many in China and abroad had assumed that the prosecution of disgraced Communist Party leader Bo Xilai would be a mere show trial — predictably scripted, with a predetermined guilty verdict. What they got Thursday, the opening day of the trial, was a show indeed.

For the first time in China’s legal history, the trial was relayed online with remarkable openness by the government, which posted updates, photos and transcripts on a live blog throughout the day. But it was Bo’s unexpectedly vigorous defense — disavowing an earlier confession to bribery and verbally attacking his accusers — that drew the most attention.

The former rising star of the Communist Party called one witness a “mad dog” and described his testimony as “the ugly performance of a person selling his soul.”

Bo dismissed the testimony of his wife against him as “very comical, really laughable.”

Political analysts and many in government remain convinced that party leaders and Bo reached an agreement before the trial about its outcome, saying that authorities would not have proceeded otherwise.

What’s unclear is whether Bo’s heated defense was part of that plan or a true surprise borne of his forceful personality and penchant for showmanship.

“His defense was genuinely surprising,” said Willy Wo-Lap Lam, a political analyst at Chinese University of Hong Kong. But Lam and others say they think even that was part of a negotiated arrangement with the government.

Both sides got something out of Thursday’s proceedings, the first day of a two-day trial, Lam said.

Bo had a chance to prove to his substantial number of supporters that he is not taking his prosecution lying down. For its part, the party can point to the vigorous defense it allowed as evidence of the rule of law and a fair and open trial.

A once-powerful party chief, Bo has been the focus of scandal, political maneuvering and negotiations for the past year and half. His dramatic fall from grace — sparked, in part, by the mysterious death of a British businessman — led to the party’s biggest crisis in three decades and exposed divisions among its leaders.

Bo had not been seen in public since party officials began his political purge. The first images of him in court became the subject of intense scrutiny. The most widely circulated photo — posted on a microblog newly created by the Jinan court for the trial — showed Bo in a crisp, white shirt, standing between two officers. On his face was a slight, enigmatic smile.

To many online, the photo encapsulated the government’s paradoxical attempts at openness and transparency while still exerting tight control over every aspect of the event.

Many Chinese bloggers seized on the height of the guards towering beside Bo. With Bo himself a tall man, they posited, authorities must have had to look hard to find guards who could make him look small.

The skepticism online came despite authorities’ unprecedented efforts to transform what traditionally would have been a highly secretive trial into a seemingly transparent and spontaneous affair. The live blogging by the government also included tweets in English by state-run Xinhua News Agency and CCTV, one of the few media outlets allowed in the otherwise closed courtroom. But with Twitter strictly banned throughout China, the tweets for some only highlighted the irony of the government’s attempts at transparency.

The online posts led to the odd scene of journalists for foreign media, who were uniformly shut out of the courtroom, reporting on the trial by retweeting the government’s live tweets.

Included in the court’s posts online were new details of the charges Bo faces: taking bribes totaling $3.6 million, embezzling more than $800,000 from a public fund and abuse of power by interfering with the investigation of the British businessman’s death. Bo’s wife was convicted in connection with the homicide.

Bo denied the bribery charge and cross-examined a witness with a barrage of questions. “I had admitted to this thing against my will during the investigation,” he said, but called it a confession “under improper pressure.”

The embezzlement and abuse of power charges are likely to come up when the trial resumes Friday morning.

Alongside demonstrating a new sophistication in using the media, the government has also employed tried and true tactics for controlling coverage of the event, issuing strict censorship orders to Chinese media, said Xiao Qiang, a U.S.-based Chinese media expert whose Web site, China Digital Times, tracks government censorship instructions.

On the day before the trial, authorities arrested two bloggers for allegedly spreading rumors and defamation online, which Xiao and other media experts say was a clear warning against controversial comments online ahead of the trial.

Reading the court’s slickly packaged tweets and multimedia posts late into the night, Qiang said, he could tell the how carefully Chinese authorities had developed their strategy to control public opinion.

“I can see the effort and seriousness they put into it. And I must admit, they’ve taken it to a whole new level,” he said.

Even so, he said, he could not admire it.

“They have achieved a kind of temporary success,” he said. “They’ve given the appearance of an open trial, but in their hearts, people still think it is all a show. They have scared some into not commenting on it, but it is a short-term delay. People always eventually express their true thoughts.”

Li Qi contributed to this report.