One cannot not believe anything that is told second hand by the news media, anymore. At times, we cannot even trust what we see with our own eyes. Governments are the same. They are institutions filled with politicians who are doing their utmost to sell the public an image and a story. Granted, there are actually still some well-meaning politicians and organizations out there, but the benefit of the doubt should not be so easily handed to an institution with a history - both ancient and recent - of so unabashedly oppressing its people. That being said, one can never actually be assured of what occurred in an instance unless they were there and involved.
The Chinese government and other governments frequently lie about stories like this. It's highly likely that they are engaged in a coverup and they did not tell the truth. It's a fairly common occurrence with countries where the government tries to control the people, which is just about every government to one degree or another.
It is no secret that China has no problem with lying and changing stories to suit their governments best interests. I have no doubt that they have falsified the story to paint themselves in a better light on the international stage. At this point, how can anyone still be fooled?
The Chinese government has shown time and time again that it should not be trusted and actively hides human rights violations. If there is some possibility that the Chinese government will appear in a negative light, it will take harsh action to block the truth from being revealed. That may include killing persons speaking out.