I don't know from the track record if there is an effective deterrent. You have crimes of passion where reason yields to instinct as well as calculated and dispassionate murders for a profit motive and many variations between those examples. In this case it was the profit motive.

While it is bizarre and wouldn't be believable if it had been a screenplay this guy intended to terrorize the population .... and did... with the motive of getting a ransom of a million or more IIRC.

Barbaric or not if ever a creep deserved to get his this guy is a poster child for the retributive value of the death penalty. I will truly have a sense of satisfaction at 9:01 tonight.