Conversation so far:
Why were the police criticized in Peter Sutcliffe's case??
West Yorkshire Police were criticised for being inadequately prepared for an investigation on this scale.
What did the West Yorkshire Police investigate in regards to Peter Sutcliffe?
The Yorkshire Police investigated the Yorkshire Ripper.

Question: Did another police department take over the case?
Self-contained rewrite: Did another police department take over the Yorkshire Police's  Yorkshire Ripper case?