Now, admittedly, they only found him in theory - island biogeographic and distance-decay theories, in fact. John Tierney discusses it all here. The finding is described in a paper (pdf) by some UCLA geography professors. Tierney quotes the paper's explanation of the relevance of geographical theory:
Distance-decay theory states that as one goes further away from a precise location, there is an exponential decline in the turnover of species and a lower probability of finding the same composition of species. The theory of island biogeography states that large and close islands will have higher immigration rates and support more species with lower extinction rates than small isolated islands.Basically, it's more likely for a species (or an individual) to be found close to where they were previously found, and more likely to be found in a more closely connected and regionally integrated location.
These theories can be applied over varying spatial scales to posit bin Laden’s current location based on his last reputed geographic location. Distance-decay theory would predict that he is closest to the point where he was last reported and, by extension, within a region that has a similar physical environment and cultural composition (that is, similar religious and political beliefs).
A doubt comes to mind - a thought that this biogeographic method might not be the most translatable to the situation of an internationally-wanted terrorist and political icon. After all, bird species on islands generally aren't trying to hide from NATO military forces. But the researchers argue that bin Laden needs decent access to resources, including electricity for his dialysis machine, so a town is a more likely hiding place. (It's true that a house or a barn is as good as a cave for hiding from satellites and drone aircraft.) And they expect that it would be a larger town "rather than a smaller and more isolated town where the extinction rate would be higher." They use the distance-decay model to narrow it down further:
When we applied a distance-decay model to his last known location from 2001, the FATA – or Federally Administered Tribal Area – of Kurram had the highest probability of hosting bin Laden (98%) (Figure 3). There were 26 city islands within a 20-km radius of his last known location in northwestern Kurram. Parachinar figured as the largest and the fourth-least isolated city (Figure 4). Nightlight imagery also shows that Parachinar is the closest city to his last known location and by far the brightest city by nightlight intensity in Kurram
You can see Parachinar here - it's that little dab of light just south of the red dot marking the last place bin Laden was known to have been.
The geographers even go on to suggest specific buildings based on bin Laden's "life characteristics" - he's tall (needs high ceilings), needs a dialysis machine (electricity), prefers high walls (bit of an agoraphobe), needs several rooms (bodyguards), and likes shady trees (satellites, you know). The most likely candidate turns out to be:
See, CIA? That wasn't so hard.