Here is an example of where evidence would be damning if not looked into correctly.
Person gets into a motor vehicle accident and kills a family in the other car. Toxicology reports on the person shows Opioids, Benzodiazepines in their system. Charges brought forward that person got into the MVA because they were under the influence, polypharamcy.
Now just because they showed up in a urine drug screen or even in a blood analysis, that simply shows the person took said medications. Further probing shows the person has an RX for both substances, has taken them for years and was due for their RX to be refilled that day or in a day or so. Considering the consistency in which that person takes their meds and based on the half life of the drugs (ER opioids, Xanax, other benzodiazepines) have long half lifes. So they could take the meds the night before, have not taken anything prior to the MVA and show the presence of taking them BUT wasn't actually intoxicated or under the influence. Of course you can do further more in depth testing for the actual levels, do they register over the cut off level, even then that does not prove without any doubt because of peak times of the drugs, individual tolerances to substances etc. Someone can take 10-20mg of Lortab, take a drug screen with in 4-6 hrs and register over the cut off yet be able to function without any signs of intoxication. It could be at or above the cutoff simply for taking the drug daily for years which would ultimately end up with a person being functional and no limitations.
So in this case, he very well could know Beasley, slept with her days prior to the murders and not actually have committed the crimes because of the residual semen and subsequent samples. So its reasonable to think they, at least Beasley had reason to be in Ozark on a Saturday night (Hawlett just tagging along), leaving a potential killer still free, and potentially falsely placing a man on to life in prison or to death.
I can describe scenarios where semen was on a person's clothing or skin, underwear in child abuse cases and people are falsely accused and tried simply based on the presence of semen on the adults clothes or sheets and were washed with the child's. Transferring onto the child's clothes.
I digress and I'm getting sidetracked