I don't think there is such thing as a sociopath, maybe under some circumstances or for short period of time but I believe that at one point or another the person has some kind of understanding of what is socially considered right and wrong. I think that the people we call sociopaths choose to ignore those feelings, and if one chooses to ignore them and participate is henious, unforgiveable acts that damage or end human life, then yes, they should be locked up. I don't believe in forever, and I think that everyone can change. No matter what you've done, I think people are capable of changing.
I don't think, that a juvenile should ever get life in prison, because I believe everything is circumstantial. I don't think there is any driving force in anyone that just makes them want to kill people, something outside of that person has to fuel their hatred and anger to get them to the point of murder (which would be the only reason I would consider putting a juvenile in prison for life). Once you take away that outside factor, with time and reasoning, I feel like that individual would be able to reenter society. I also do not agree with the death penalty whatsoever for anyone. I don't think any human has any right to decide if someone lives or dies.
I think rehabilitation is good, and upon reentering society the juvenile or any other individual needs to be surrounded by other people that share the same vaules and goals as them as to make it easier for them to stay on track.