Physician Assisted Suicide for Criminals?

Sort of playing off of the "Death Penalty" topic..Should there be a system available for criminals set to serve life+ sentences to "opt out" so to speak with an "assisted suicide" type set up?

Rather than the death penalty, the criminal essentially chooses that option as opposed to serving out a sentence til death.

What problems could this create, other than some believing that the criminal deserves to live out a life in prison, or some viewing this as an "easy way out".

For me, it just doesn't set right. I can't quite articulate why, but would love to hear your thoughts.