I would just say that every case is different. Leopold and Loeb (the crime of the century) killed a kid just because they thought it would be fun (which seems even more senseless than this prom case). They wanted the rush of creating a mystery nobody could figure out and they relished in their genius...then they got caught.
Loeb died in prison. Leopold was released 33 years later. He used the royalties from his book to start a foundation for "emotionally disturbed, retarded, and delinquent youths". He went onto teach and practice medicine in Puerto Rico and was very active in the community.
People wanted him to get the death penalty. They thought these guys should never get out of prison because they were such a danger. Point is, you don't know.
Maybe this kid deserves to die. Maybe that's justice. But whether or not he can be a good citizen some day is totally unknown.