I know from ex police..how they would know someone was a perp in cases. yet their hands were tied. They just could not make an arrest until they had the evidence that would stand up in court. Otherwise they loose the chance at conviction if they don't do it all properly. Definitely frustrating.
They must feel fantastic when their hard work pays off and an arrest is made. We really don't give enough credit as a society maybe? Bittersweet - an arrest is made... but still 3 girls no mum, 2 parents no daughter. Hats off to the police!