In September 2001 Zarqawi was in Iran, not in Afghanistan. He only went to Afghanistan after our October 2001 invasion. After that he fled, wounded, to Baghdad.
Jordan asked the Saddam Hussein to extradite Zarqawi so they could try him for his role in the Millennium plot to bomb sites in Jordan including a hotel frequented by Americans [and Israelis too, IIRC].
Saddam refused the request.
After treatment [and after his cell in Baghdad decapitated a nun] he traveled north. In late summer 2002 he was in Syria where he had a training camp and it was the Syrian cell who assassinated Foley in October 2002.
All this before the US invasion of Iraq.