Would he be cast from Heaven for killing people?
Not if he repented to God, was willing to be owned by Jesus, and completely trusted in Jesus to save him from his sins and sinfulness.
No joke.
God forgets when the heart is washed clean and the sins are washed away by Jesus' blood!
Like He did for me . . .
"God has blotted them out, I'm happy and glad and free!
God has blotted them out, you can turn to Isaiah and see:
Chapter forty-four, twenty-two and -three.
God has blotted them out, and now I can SHOUT,
For that means ME!"