What should we do with sex offenders?

I personally think that if they have committed the crime and have done it repeatedly that they should be put somewhere where they cannot do it again, even if it means being put in prison for life. They should not be able to be put back on to the streets, especially by schools or areas of the ages that they are going after. What i mean is, if they have victims that are between 5 or 10 then do not put them by those areas. It might actually solve some of the problems.
It also depends on what kind of sex offender they are and what level they are at. If they are a level 3 sex offender than I think that they should definitely be put behind bars for life and/or death. I do believe that some people can change but usually being a sex offender means there is something mentally wrong with you. No sane person would just rape women or guys for the hell of it, there has to be something wrong with them.