I got spanked as a kid (rarely... maybe less than a half a dozen times and only for significant misbehaviour) and I survived fine. It's only a problem when the parents hit too hard (I don't think hitting with rulers or wooden spoons is a good idea...) or too often, for dumb things like failing a spelling test or having a messy bedroom or something.
Also, I remember once mum literally washed my mouth out with soap after I used foul language. Now that was a threat I never expected her to actually follow through on!
But anyway. A kid this antisocial is well beyond the control of normal discipline... spanking or not-spanking doesn't influence kids into becoming murderers. It's totally aberrant behaviour.