Soon after a fire on a crowded commuter bus killed 47 people and injured 34, Chinese authorities offered an explanation: One of the dead had written a suicide note, boarded the bus during the evening rush and set it on fire.

After doubts were raised online, police said they found pieces of the burned cart and woven bag the arsonist used to transport gasoline. They said survivors saw Chen Shuizong set the fire, and that his wife and daughter confirmed that the suicide note was written in his handwriting.

Many Chinese still aren't buying it. Their reaction reveals at least as much about their distrust of the government as it does about the June 7 fire in Xiamen, a prosperous port city in southeast China's Fujian province.

"How can you solve a case in such a short period of time?" asked Liu Shanying, a political scientist at the Chinese Academy of Social Sciences. "And the suspect is dead. From a legal point of view, the case just looks very suspicious."

China's authoritarian government tightly controls access to information, censors the media and regularly refuses to provide data. Incidents of authorities or officials denying an event or guilt only to later be found to have been lying have added to citizens' distrust, as has endemic corruption.

Police changed their story twice following an explosion that killed four people last year at a community center in southwest Yunnan province's Qiaojia county. Twelve hours after the blast, they said a woman with a 1-year-old baby was the perpetrator. Days later, they named a different suspect and stated categorically that he was responsible. Three months later, two other men were named the criminal suspects.

Last month, authorities announced in a terse statement that they were investigating "suspected serious disciplinary violations" by Liu Tienan, the deputy chief of the planning agency in charge of steering the Chinese economy. But that came months after an agency Liu worked for fiercely denied a prominent journalist's accusations that Liu had shady ties with a businessman, was involved in large, problematic bank loans and had made up his academic qualifications.

Such backpedaling has made Chinese more suspicious of the official versions of events.

In the case of the bus fire, police on Monday offered a greater level of substantiation than usual, but skeptics are demanding more. They want to see the suicide note, which has not been released, and any video that may have been taken inside the bus.

"So many suspicious points if you really think about it," said Xie Tianming, a photographer who is based in Fujian. "How is there the space for a person to pour out gas and light it in a crowded place? And no one saw it to stop it? No testimony from survivors? Where is the driver? Who can believe the lie that in this high-tech era we can't get surveillance footage?"

In a microblogging account reported by state media to be Chen's, the writer claimed to be destitute and pleaded for an opportunity to live. The writer chronicled his frustrated efforts to get a local police station to correct his age so he could be eligible for social security payments. The last entries were made a day before the fire, and the account was removed a day after the fire.

Some question how an impoverished man needing social security could afford a computer, or that a man of his age — born in 1954, according to authorities — knew how to use the microblogging site.

"A confession online, and an identity of petitioner makes one a suspect," lawyer Liu Xiaoyuan wrote on the Sina Weibo, referring to people who take local grievances to the central government. "It is lucky there was only one petitioner on the bus. What if there were more? It would be seen as a group alienating themselves from society. Why doesn't the police release the evidence directly?"

Such doubts are voiced every time China has a violent episode that the government blames on a loner. They illustrate the tensions between a government that wants to control information and citizens emboldened to question official accounts online where, there is lively debate, criticism and access to more information than ever.

"People are becoming even more distrustful," said David Zweig, professor of social science at Hong Kong University of Science and Technology.

"In general, society in China pays a huge price for all kinds of government abuse or for company misbehavior," he said. "That's the main theme in China these days and so if this guy cracked because of one of those situations the entire bureaucracy has no interest in it being publicized ... And the Chinese people know it."

In some cases where doubts surfaced about the official version, the perpetrators became instant heroes online.

In 2011, Qian Mingqi, a man upset over a long-running land dispute with the government, set off three bombs in the southern city of Fuzhou, killing himself and two others and stirring sympathy among a public angry at official corruption and indifference.

After state media identified him as the culprit, Qian's blog drew hundreds of messages, many of them admiring, and he garnered thousands of followers. Today, he still has more than 20,000, and people continue to leave messages.

One says, "Came back to visit Mr. Qian after the Xiamen fire case."


AP researchers Flora Ji in Beijing and Fu Ting in Shanghai contributed to this report.