What Did the ISI Know, and When Did It Know It?

So let's get this straight: Osama bin Laden was living in a mansion in Abbotabad, a fair-sized city not far from the Pakistani capital, Islamabad. How long was he there? How could it be that the ISI, which has the country wired, did not know he was practically next door? For all we know at this point, the ISI was directly involved in fingering Bin Laden. But there are an extraordinary number of questions that need to be answered.