My grandfather told me about a neighbor of his who was assaulted by her burglar.
As they wrestled she struggled to get to her gun in a drawer near the front door.
When she succeeded, gun in hand, the burglar fled out the front door.
She emptied six rounds into his back, ran back, reloaded, and continued to scream for help, her gun trained on the bullet-riddled corpse.
To her he was STILL A THREAT; retreat didn't automatically mean that she was safe.