Police at first said that Crimo was not known to them but on Tuesday, they revealed he was interviewed twice by authorities in 2019.
The first was in April 2019 a week after he threatened to kill himself. The second was in September 2019, after he threatened to 'kill everyone' in his family.
Police recovered 16 knives, a dagger and sword from his home but he was not arrested.
Instead, he was able to turn 21 and buy two assault rifles in Illinois, along with three other types of gun. It remains unclear why the two previous incidents were not flagged when he legally purchased the weapons.