The cat went feral right inside the house. Some are just predisposed to not accept domestication, no matter how well fed they may be.
Sometimes euthanization is the only option. Bad behavior in cats is not an easy condition to bring under control, if it is at all possible.
The cat could have something as drastic as a tumor or another serious nervous system disorder.
Man.. thought you were talking about my cheating ex-wife for a bit there .. o.O
Jackson Galaxy can help any cat.