http://www.reuters.com/article/us-mideast-crisis-iraq-britain-militant-idUSKBN1611A8Originally from Manchester, UK. Converted to Islam in his 20s. Detained in Afghanistan by US Special Forces folks and was sent to Guantanamo in 2002. The UK govt threw a fit, and we released him in 2004. He sued the UK government after his release and received up to a million pounds in compensation. There's disagreement on the size of the settlement.
At some point after that, he went to Syria to fight with Islamic State. Recently, Ronald Fiddler aka Abu-Zakariya al-Britani blew himself up in Iraq with a car bomb.
There's a reasonable argument that quite a few people were radicalized in Gitmo. But if someone was captured in Afghanistan, odds are quite a bit lower of that.
