If you’re going to be an apologist for a predator at least understand the situation. It looks like you are arguing just to be contrarian- not a good look in this case, highly insensitive given the type of crime we are discussing.
He did not serve his full eight year sentence. He was transferred back to Holland from England to serve the remainder of his eight year sentence - and was released the same year
So to answer you: No he absolutely did not serve his sentence