Blackmail

After reading more about the case Bill understood police too were actively looking for them, they also speculated that these two were serial killers who committed more crimes and killed old men in the nearby towns but it was just a speculation and there was no concrete evidence.

Bill started thinking what could be the relation between the murderers and this old couple, he thought, 'I am missing some link, what is it? Something is missing. Think Bill think, think harder' He again read the article and keenly observed the rough sketches of the culprits, suddenly something stuck in his mind. 

He realized the two old people were Andrew and Sophia in disguise, 'now it all makes sense' he thought as he heard loud sex noises coming from their room, he witnessed that bag full of currency, their voices sounded young in the recorder.