you should have reported it to the police and film how they cordoned off the area and removed the evidence. They are good in doing such things as it makes them feel they protect the public and they do not have to fear viollating someone's humans rights.
However, I'd guess it was actually planted there on purpose to study the response of the public and to figure out who would pick it up. You should have looked for the hidden camera. It's either some of your colleagues , part of a study of human behaviour or the big brother team in the hope to find something else to broadcast - or was it you QorbeQ