1. Remove from society, with no additional cost to society. 2. Signaling to dissuade new offenders.
You can go one step further and punish the family, parents, and friends. Seems to be happening in the US for underage mass killers.
It’s a simple, effective, and low cost way to deal with crime of the highest magnitude. Why should it be off limits for corruption?
Also, who would be deterred by the risk of execution, but not deterred by the risk of a life sentence?
Claiming harsh sentencing is a deterrent is a convenient cover for the real reason - it's about revenge. Because it very obviously isn't a deterrent, at least, not an effective one.
Unless US states that execute people have dramatically lower rates of murder than states that don't, in which case, I'm wrong and stand corrected.
Guess it depends which of rehabilitation or punishment you value most.
Death penalty should be: take a life, pay with your life.
There is no need to consider deterrence in any shape or form.
The concept of deterrence being a reason for capital punishment only bolsters anti-capital-punishment arguments.
Fair punishments may deter insufficiently. The deterrent effect involves the probability of being caught and convicted. A law enforcement and criminal justice system that is not effective at catching and convicting can just crank up penalties to keep the deterrent effect high.