I concur with you that the investigators or the 12 LE agencies involved in the investigation are not involved in any type of cover-up. However, mistakes were obviously made early in the investigation.
As far as me changing my mind, I will just say I have a lot of mixed feelings about the identity of the killer or killers. I originally thought it might have been a police impersonator or a rogue police officer acting on his own. Then, I shifted to the girls being killed by someone they (well JB) knew. But, as the investigation has lingered for 19+ years, I've started to realize that if these murders were something simple and the motive was obvious, the case would have solved the case by now. Then, this past winter, I received a tip from someone who gave me some info I feel is very solid. The person they were suspicious of was a stranger to the girls. The info was passed on to LE. Time will tell if the info is good or not.
Is there a reason J.B seems to be considered the connection to the killer rather than Tracie? It doesn't sound like she had the best home life but she seemed like a good kid. I'm not suggesting either girl is to blame but the killer could have been acquainted with Tracie or with someone in her family. The killer or killers could be strangers and those girls were in the wrong place at the wrong time. I feel like J.B has been portrayed by some people as a trouble maker or wild. It doesn't seem fair and hopefully it doesn't keep law enforcement into looking at people in Tracie's life too.