How to use "perpetrator" in a sentence

She had an almost psychic sense that the perpetrator of this viciousness was in the building now, perhaps on the third floor with her

Elliot didn't tell the judge about the malicious prankster, for that seemed like an unnecessary complication; he still believed that once the fact of Danny's death was established by the exhumation, the quickest and surest way of dealing with the harassment was to hire a first-rate firm of private investigators to track down the perpetrator