Honestly, I don't really remember all the details -- remember, she was telling me this like 2 days after the attacks. I think they were shown pictures, or maybe she saw pics in the newspapers. But both she and her fiance recognized them.
Much of that first week is still a blur to me, but I *think* that one of the ones who nearly crashed into them was Mohammed Atta. They were definitely from one or both of the planes that hit NYC, because I remember both of us getting weirded out when we realized the "connection" between us because of this.
What they noticed was that these guys met up in the parking lot with some other Arab-looking guys in a van or SUV or something, and were furiously exchanging boxes and packages between the two vehicles.