Conversation so far:
what is ai weiwei  release referring to?
On 22 June 2011, the Chinese authorities released Ai from jail after almost three months' detention on charges of tax evasion.
what evidence did they have?
had allegedly evaded taxes and intentionally destroyed accounting documents.
how was he treated in prison?
his sister gave some details about his detention condition to the press, explaining that he was subjected to a kind of psychological torture.
what did they do to him?
he was detained in a tiny room with constant light, and two guards were set very close to him at all times, and watched him constantly.
was he subjected to any other mistreatment?
Ai also mentioned that his detention by the Chinese regime was hellish (Chinese: Jiu Si Yi Sheng ), and stressed that he is forbidden to say too much to reporters.
what was he charged with?
Ai's supporters widely viewed his detention as retaliation for his vocal criticism of the government.
what did the public think of his imprisonment?
Ai's supporters widely viewed his detention as retaliation.

Question: did they have evidence against him?
Self-contained rewrite: did the Chinese authorities  have evidence against Ai Weiwei?