Mark David Chapman, the deeply disturbed, possibly schizophrenic killer who gunned down John Lennon in 1980, was denied parole today for the fifth time. It was the right decision, even if at this point it's unclear whether society needs to be protected from Chapman or Chapman needs to be protected from society.

There was never any trial for Chapman, who was sentenced to 20 years to life after he pleaded guilty to second-degree murder. To many Lennon fans, that seems like an injustice given that by Chapman's own admission the 1980 killing was premeditated: Chapman staked out Lennon's Central Park apartment building, the Dakota, for days before the opportunity arose to pump four hollow-point bullets into the former Beatle's back. That should have guaranteed life without parole if not the death penalty for Chapman, except that the killer was so unhinged that had the case gone to trial there's a strong chance he would have gotten off on an insanity defense.

Today, Chapman is housed apart from the general population at Attica prison because of his notoriety. But if he's in danger from Lennon fans among his fellow prisoners, it's not hard to imagine (no pun intended) somebody pulling a Jack Ruby on him if he ever gets out. I'm all for being sympathetic to the mentally ill, but Chapman should stay in prison until he dies.