The Death penalty and Dexter

Because of our justice system, Dexter, if caught would be sentenced to death because some of the people he kills are people who were guilty, but proven innocent and therefore is innocent.  also a murder is a murder whether it is to kill others who kill or not.  The death penalty itself is legal in some states because it is executing a person found guilty beyond reasonable doubt the way. Dexter carries out his own death penalty is not legal it is execution people he finds guilty beyond reasonable doubt not the justice system.  What he is doing is just in his eyes but isn't it just to some of the other murders in the show who killed for a reason, they don't expect to get caught as much as Dexter.  The excuse of him not being able to control it is not a mitigating factor and neither is his life growing up torturing animals because he cannot control his impulse.