Conversation so far:
What did Ai Weiwei release?
On 22 June 2011, the Chinese authorities released Ai Weiwei from jail after almost three months' detention on charges of tax evasion.
What did Ai Weiwei do after his release from jail?
After Ai Weiwei's release, his sister gave some details about his detention condition to the press, explaining that he was subjected to a kind of psychological torture.
What kind of psychological torture was Ai Weiwei subjected to?
Ai Weiwei 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.
How did the press respond to Ai Weiwei's release?
Was Ai Weiwei found guilty?
The release of Ai Weiwei on bail shows that the Chinese government could not find any solid evidence of Ai's alleged economic crime.

Question: Was he investigated for anything else?
Self-contained rewrite: Was Ai Weiwei investigated for anything else besides his alleged economic crime?