Listen anon, this was deep in my time, heck i'm still fighting for it. All i want is a re-investigation. But at this stage it's almost a lost cause because there's now bigger things.

I could spend hours on this, but to save time just look at some of these videos:

50 Questions They Can’t Answer About 9/11:

Part 1: https://www.youtube.com/watch?v=bVYpZeH3Cqw

Part 2: https://www.youtube.com/watch?v=XdRmnk6Q1VI

Part 3: https://www.youtube.com/watch?v=UxF4HL-kIfo

The above series is LONG and IN DEPTH. You will learn a ton.

9/11: Explosive Evidence - Experts Speak Out:

60m video: https://www.youtube.com/watch?v=Ddz2mw2vaEg

The above video is fantastic and forms the basis of a scientific reason for a re-investigation.

University Alaska Fairbanks research

https://ine.uaf.edu/wtc7

So the above is some research that UAF did to determine: did WTC7 fall due to fire? ultimately they answered: it was impossible for it to fall due to fire.

Bonus: the Asch Experiment (funny, but sad too): https://www.youtube.com/watch?v=RpmKy9ZESTo ) <-- this video explains the science behind why so many normies refuse to go with the truth (they prefer to follow the crowd).

ULTIMATELY: to answer your question - yes the FBI 'investigated' it, but no they did not investigate it.