I'm going out on a limb to say that the punishment did not fit, now if they would have revived him and then proceeded to bury him in a semi conscious state well then yes it would be some what more fitting , ... IMO.
This animal shotgunned a young female and buried her alive ,The story quoted him as saying that his biggest fear was a painful death so I wonder what his fears were when he blasted a young lady with a sawed off shotgun and then buried her ALIVE , .. sorry no sympathy here.
*edit- Better yet just bring back the firing squad and or hanging , history shows those methods were very reliable.