I think if that person had been treated with compassion they might not have come to that. I think we're no better than him if we torture him. I believe he should be apprehended and forfeit his freedom for his crimes, but I don't think it's for us to take life, especially given a flawed system which wrongfully convicts with regularity.
Compassion is as much for us as for him. It does no good to harbor hate, and it darkens the soul.