I assume the author is not a Facebook friend with the girl. Otherwise it would have been too easy. But friends of friends is not the only privacy leak on Facebook. There is a very old feature (which is about to get deprecated) called Networks.
Networks are created for schools, universities and other big organizations. They had the name of the high school so they have to list it as their own high school in their Facebook profiles.
This will automatically put them in the same network as the girl. I am assuming here that she has listed that on her Facebook profile.
Then performing a graph search for women who has gone to that high school and live in Austin with an age between X and Y will narrow the search a lot. Even if some of that information is not public on Facebook it would be public to them if they are not same network if she has the default settings. This is a neat trick which is still usable.
I don't think looking through the pictures would take more than half an hour.