The brilliant characterization of Justin by Michael Pitt in 'Murder by Numbers' really impressed upon me how morally wrong the death sentence is.
Here we have two teenage boys. One is intellectually brilliant but in all other aspects a very naive juvenile. The other is worldly, spoiled, controlling and manipulative. He is also violent and cruel; contemptuous of women. We see in the film that he kills and is eventually killed himself.
The cruel twist at the end of course is that the character of Justin has also killed. But the two murders and the two characters...