I don't think many killers are deterred by a maybe long sentence - that's not on their mind when they kill.  a potential sentence doesn't deter a  pre-meditated murder  - just cover your tracks, right?  if someone who has committed a bad enough crime to think that murdering their victim is the way out  probably didn't need that added umph anyway.  they are either just criminally minded, not capable of forming their own intent or ..?, a relatively low IQ..?.   there are of course exceptions, always are.   keep in mind how much is spent per prisoner.  after finding out someone close to me was a long-time serial pedophile, after reading his long-time, on-going public record of crimes - sad, these people cannot be fixed.  they are hard wired to want what they want.  it is what they want and there is no substitute.  so yeah, either physically castrate these guys, not at all  unusual for them to quit the chemical castration or - hate to say and hard to say - execute them.  it's hard to say.