This case, and other cases, demonstrate why “life in prison” doesn’t mean what is stated. Sooner or later almost all of these “things” are released back into society. At our peril.
The death penalty is the correct answer to those who murder. By their actions they have forfeited their right to live.
This may sound draconian to some, but IMHO, capital punishment ought to be on the table as an option for prosecutors for any crime in which the victim would have been justified resisting with deadly force.
In such cases, it is the criminal who has openly declared the fruits of the crime were of a greater value than their own life. Let them reap that harvest.