Goodness.
If every domestic abuser shot a police officer every time he attacked his ex or partner, the police would take domestic violence an awful lot more seriously, wouldn't they?
Durham prison told the police that he was threatening to harm his ex girlfriend. I suspect that if they'd told them he was threatening to harm a police officer, the police would have apprehended him before he could get hold of a gun.
I presume the reason he was released was becuase his sentence had actually come to an end and they couldn't continue to keep him in gaol, even though he was making threats against his ex?