That's a good example of thorough police work. You have to wonder if too many LE and prosecutors today think they have to have a DNA match for every perp before they make an arrest, when old-fashioned investigative work is just as important. Today, you wonder about some cases when it seems LE only looks for DNA and waits for the public to call in with tips to solve the case. It's still necessary to use the shoe leather - get out and talk to people, follow up, check and re-check alibis, etc. They need prosecutors who are energetic, skilled and experienced enough to build cases on more than just DNA evidence.
If these 4 crime scenes were so sterile, if the perps left so little evidence behind, they wouldn't be locking up all the homes. There has to be evidence available to them - cell phone, internet records and other evidence found at the crime scene. If, as they claim, the killers are local, it shouldn't too difficult to build that case.
As for locals not caring if the crime is solved - it's hard to believe people could be that ignorant and uncaring. An entire family was killed, including young people who hadn't lived long enough to deserve that kind of death. No human being deserves that. Regardless of local opinion, the public demands that cases be investigated and killers caught and punished.
I would certainly hope those with irrational hatred of the Rhodens don't think it's ok for killers capable of ambushing and killing 8 people to walk around in the community, free to kill again. That's a very sick POV, IMO.