(a) When any person shall be convicted of murder, rape, carnal abuse, or kidnapping and it shall be shown that the person has been twice previously convicted of any of the above-mentioned crimes in this state or any other state, upon the third conviction the person shall be deemed a habitual criminal and shall be sentenced to life imprisonment in the Division of Correction.
(b) However, nothing in this section shall be construed to abolish or otherwise affect punishment by death for crimes which are punishable by death.