Well it seems to me as if the grounds for his conviction was somewhat questionable.  The charges against him was mostly based upon tapped telephone conversations.  In these telephone conversations the Al-Jazzera journalist Tayseer Alouni talks to suspected Al-Qaeda affiliates about some "trousers" and about "Syrian bread".  The police seems to have interpreted this as some kind of code, while the journalist himself says that his conversations was perfectly in order and was in fact no code at all.  Bear in mind that Mr. Alouni had and presumably still have, lot of friends in the Syrian community in Spain him being of Syrian background himself.

According to the police theses codes were used to coordinate a courier transport/messages system between different Al-Qaeda cells.  He was also accused of aiding the 9/11 bombers in 2001 but was acquitted of these charges.  

Here's a link to a interview with Tayseer Alouni from august 2004 about the charges:
  http://www.abc.net.au/foreign/content/2004/s1177292.htm

 

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