It's not as simple as that!
There was an interesting thread a while back discussing the death penalty. I think it was over Timothy Mac Veigh (?sp).
One thing that transpired was that it costs more (? twice as much?) to carry out the death penalty than it does to keep someone in prison for life.
Two words: Legal costs!
As far as I can remember, someone effectively has to have a retrial before they can be executed - this is where the money goes
Nice looking rifle, BTW
I used to do a bit of .303 shooting at Bisley range (UK). 200, 300, 600 & 900 yards.
It would have been more fun shooting nonces, though