Proper Penalties

I noticed news came out recently about a study that indicated use of the death penalty did appear to deter murders. That caused ethicists to say that perhaps we needed to reweigh the moral pros and cons of the sentence.

Perhaps we should consider other things: Cut off the hand of a thief; castrate rapists; cut out the tongues of liars (i.e., people who commit fraud). I strongly suspect those penalties will lead to a reduction in the related crimes.

Or are there other moral factors that need to be weighed here?