Steel was removed from 9/11 as soon as possible, does that means they tampered with a crime scene?

Building 7 came down at free fall speed. This was verified by the NIST report 7 years after 9/11/01, meaning they intentionally waited an excruciatingly long time for a CRIME SCENE. The steel was removed from the world trade center area, that's criminal, you can't remove evidence at a crime scene. The FBI confied video of the pentagon crash and refuse to show it to the public. This is in violation of the freedom of information act, and once again, hiding evidence of a crime scene. If the government didn't look the other way, and actually wanted to preserve justice, what kind of action do you think the government would do to ensure justice?