There was absolute proof of jumping. They jumped, they did not stumble or fall. You don't see the pictures, because the main-stream media thought it was too horrific for us all to see. IMHO, each and everyone person should see how horrible it was. However, their families need not be questioned about it. It is horrible to see an anonymous person facing such death. It does not seem right to approach their loved-ones for the gruesome details.
http://www.twin-towers.net/jumpers.htm
This site is graphic.
Never forget.