My opinions only, no facts here:
As this case develops, keep in mind the subject of skin-cell DNA, or more recently called- "touch DNA". This article at
http://www.ryanforensicdna.com/yahoo_site_admin/assets/docs/Touch_DNA_article.5151606.pdf will bring you up-to-date. DNA testing is almost too sensitive now to be fully reliable as evidence. Have you ever thought about how many individuals' DNA could be located in your home, using current methods? The number of individuals could range from hundreds to more than a thousand. Think about those who lived in your home before you occupied it. How about DNA transferred twice or thrice before it reached your home? Think about every utility worker. Think about every piece of mail that was ever in your home. Every piece of used furniture you ever bought. Every book. A strong wind storm that blew much dust into your home. And on and on.
Remember this post if the current suspects in the Holly Bobo case are ever brought to trial. DNA testing has moved far beyond sampling a bloody glove hidden under a suspect's bed. It now is so sensitive that it can almost guarantee some sort of hoped-for result. It is increasingly important for competent jurors to consider the CONTEXT of a damning DNA sample. If the DNA evidence is from a proven murder weapon that has fingerprints, it may be OK. If the DNA evidence is from some random location AND is touch-DNA, remain skeptical. Remember, somewhere out there is a rug that contains DNA evidence of a capital murder, and it may be for sale in a second-hand store! Don't buy this rug! Use your Star Trek tricorder to scan its entire history of DNA before you purchase it. Otherwise, you may have the hoosegow in your future!
Having said this, how can an astute criminal take advantage of this extreme analytical precision for DNA? Remove the daily sweepings from a Barber Shop AND a Pet Groomer AND a Shopping Mall (out of their respective dumpsters), and spread these around your pre-planned crime scene. This would deluge any traces of your DNA and it could cost tens of millions of dollars to analyze all of the DNA! You see- DNA is increasingly becoming less relevant than fingerprints (unless you can extract DNA from the print), because a fingerprint is only spread to a crime scene in one manner and DNA can be spread to a crime scene in a zillion manners.
I have to laugh when I see a TV crime show where the investigators spray "Luminol" on the carpet to prove that a crime has occurred (the inference is that Luminol reacts only to blood). Luminol is activated by the presence of iron, copper, or other metal ions (see
http://www.angelo.edu/faculty/kboudrea/demos/luminol/luminol.htm). When you examine compounds that contain iron, copper, or other metals, you are basically examining a panoply of compounds historically spilled or purposefully used on the carpet, from blood to paints to cleaning products! In my opinion, Luminol evidence should only be used when it detects an area from which blood-DNA is also confirmed to exist.
For a big laugh, take a black-light source (in the dark) and have a good look at the historical stains in your carpets. Assuming that your black-light frequency is correct, it will look like thousands of crimes have occurred in your home! I demonstrated this principle to my kids when they were little and they had a huge laugh about it. Unfortunately, there are a lot of Yardbirds marshalled into the Pokey who are not laughing about such subjects.
Sleuth On!