> Throwing the person into prison for life is obviously the wrong solution, it is not proportional to the crimes committed and it's a net negative for society.

That brings to mind an interesting question. Why should prison time be proportional to the crimes committed?

If the purpose of prison is rehabilitation, then shouldn't the time be however long it takes to rehabilitate the prisoner? There might be some correlation between that and the crimes committed, but I would expect that to be a weak correlation. There will be many people who are easy to rehabilitate whose first crime was very serious and many people hard to rehabilitate whose first crime was relatively minor.