I'm upset

This is just a silly rant about how upset I am after watching the channel 7 special on Cheryl Coker. The news station themselves did great putting together details/timeline but what makes me scratch my head is the fact that they have so many details sorted but just can't seem to find enough damning evidence to get this family justice. They brought in a Chief detective who was head of the Erica Baker case to help, but what I don't understand is how both cases have a person of interest and a lot of damn information but nothing can be done to get justice. My question is, did the police drop the ball on these cases or was there nothing they could have done differently? I feel if Cheryl could have been found faster some sort of DNA evidence or marks could have helped them catch the person responsible.