Where did you see all that?
Where are the books written about him? Wheres all the websites with slueths looking into his past?
Etc......
The information was in articles about him during the period after his committing of mass murder. As I recall, there was quite a bit of coverage during the next couple of months.
One of the people who sold him ammunition was even charged and convicted of some relatively obscure federal gun law. That guy got a prison sentence out of it.