He was dormant for over 30 years after his last attack. Strange how all of a sudden he just stopped raping and killing.
Old age?
The video talked about him jumping fences and parking several blocks away so when the police rushed in, he could just drive away with ease.
Maybe he felt a little sore/sloppy/out of breath his last attack and realized he no longer could pull it off. If part of the thrill is getting away with it and you know you've lost the ability...