It is up to the police to decide if the suspicion is reasonable based on factual evidence and deserves more attention.
In this case it did.
In this case, suspicion had nothing to do with it. There were eyewitnesses to at least two incidents: one of Sandusky in the shower with a young boy and the other an actual rape of a young boy.
Actual suspicion is based on very little in the way of observable evidence Suspicion is hunches and impressions based on suggestive evidence such as behavior or coincidences, and not eyewitness evidence to a crime or highly inappropriate behavior.