O’Hare’s invisible man. How does someone live at the airport undetected for nearly 3 months?

Questions abound in the bizarre tale surrounding Aditya Singh, the man found living at O’Hare International Airport for nearly three months. The biggest is the most obvious: How could security personnel at O’Hare, one of the world’s busiest airports, fail to notice someone living in a secured area, turning it into his own Airbnb?