Looking at the wider picture of nature/nurture deebate within the criminal fraternity, it throws more questions than answers.
Firstly, I want most criminals too hang, especially kiddy fiddlers and murderers. However, I also believe that many sickos are born bad.
In essence, that means I want to see somebody hanged for a sickness. That would be like punishing the blind or spastics for merely being born that way. This, naturally, is an abhorrent idea.
So.................my view. I follow the above insofaras we all have free will (unless clinically mad, in which case they are institutionalised in a looney bin, as opposed to prison). Therefore a criminal decides his actions.
I do not buy all the weepy left wing woolley answers about drug users, for example. "They live on the streets, their lives are worthless, blah blah blah". They choose to inject drugs, society or even mental instability can not inject can it? It's their own free will. In the same way, Peter Tobin murdered. Society can not be held responsible for such actions, like marxists want us to believe.
I can further liken the simple burglarly. A person who needs drugs MAY burgle a house to feed his foul addiction. But why do a high percentage of them trash the place as well? Why would they steal war medals and jewellry clearly of a sentimental value when equally priced things are available? Why, because they are born bad. Simple as that.
The drug-addled burglar who steals DVDs and CD's etc, are still scum but at least they have some degree of conscience.
As for Tobin. The man was born bad which probably manifested itself through a degree of bad luck in life. He deserves to hang, and may the noose snap half way through, thus enlongating his sufferring.