Complex sentence: CSIS has alleged that during this time he also worked for Human Concern International, suggesting this meant he was a formal colleague of Ahmed Khadr, and that he may have run a guest house for foreign mujahideen traveling to participate in the Afghan civil war.
Split into simpler sentences: CSIS has alleged that during this time he also worked for Human Concern International. They suggest that this meant he was a formal colleague of Ahmed Khadr, and that he may have run a guest house for foreign mujahideen traveling to participate in the Afghan civil war.