Conversation so far:
What happened with the BALCO scandal?
Late in 2003, Giambi was named by FBI officers investigating the Bay Area Laboratory Co-operative (BALCO) as being one of the baseball players believed to have received anabolic steroids.
Was he found guilty?
In a press conference prior to the 2005 season, Giambi apologized publicly to the media and his fans, though he did not specifically state what for.
The.
How did his fans react?
CANNOTANSWER.

Question: What was the evidence against him?
Self-contained rewrite: What was the evidence against Jason Giambi?