That's Some Mighty Fine Police Work

The Aurora shooter, despite having been convicted of a felony in Mississippi in 1995, had successfully passed the background check to obtain a Firearms Owner ID (FOID) card in Illinois.

He then managed to pass a second background check run by the Illinois State Police, Illinois is a Full Point of Contact state with an:

"[agency] acting on behalf of the NICS in a full Point-of-Contact (POC) capacity. These POC states, which have agreed to implement and maintain their own Brady NICS Program, conduct firearm background checks for FFLs’ transactions in their respective states by electronically accessing the NICS. Upon completion of the required ATF Form 4473, the FFLs conducting business in the POC states contact a designated state agency to initiate a NICS background check in lieu of contacting the NICS Section."

Florida is also a full POC state.  It just means they (we) keep our own database on who's ineligible and it almost certainly contains the NICS data.

I'm going to bet that Mississippi didn't report the conviction correctly and it was misplaced in the database or absent.  At first anyway.

The shooter, in 2014, tried to get a conceal carry permit.  This is where his past finally caught up and the background check noticed his conviction and felon status.

The Illinois State Police also notice his FOID and gun purchase (tell me again about how FOID and universal background checks aren't registration) at this time and write him a firmly worded request that he surrender the gun.

Five years later... he uses that same gun to murder five people and wound some cops trying to stop him.

Another mass shooter that could have been stopped if the police and law enforcement agencies had just done their jobs?

Shocked face not found.

If ever there was a narrative that more clearly illustrated that gun control isn't about stopping criminals but making the lives of the law abiding needlessly more difficult; this is it.