Screening
I don't agree with Snyggapa assumption unfortunate deceased person was not screened. Such a person seeking to reach destination of aircraft could obtain basic airport employment not needing to pass security with forbidden goods. He might move clothing to locker or drawer over a period then access aircraft just before departure. To my mind no security failure is indicated. During the 80's mysterious bodies were being found in the London suburbs, sometimes on a rooftop. Only when a frozen one was found did the penny drop.