The only problem with that...
is those convicted sex offenders that are released and wind up killing someone did not kill the first time.
Do you know of a situation where a child killer has been released to kill again? Stupid (or non-stupid) releases by some judge prior to trial don't count. There may be cases but they are anomalies. Child killers are usually executed or get life w/o parole. Life must mean life.
I would put child sex offenders away for life on the first offense unless they could be reliably de-sexed and even then under some halfway system for 10 years or so