This they did to a certain degree. But, answer this. After it was clear that the parents were lying, about drugs, etc. WHY DIDN'T THE POLICE INVESTIGATE FURTHER?
Can you compare the investigations done to the Jahi Turner case, where the boy disappeared from a park, but the police turned the residence of the parents into a POLICE INVESTIGATION SITE,and wouldn't allow ANYONE INSIDE?
At the Van Dam's, they allowed neighbors,friends, strangers to come in and cross contaminate,clean up, have parties, etc. while investigations were going on. (I have embellished only slightly, but I will admit some)