I wonder if they have those 30-35 human cells needed though. Or if maybe that DNA ended up being not related to the crime. Perhaps matched to someone with a totally solid alibi ... just trying to think of some ways the DNA might not have panned out, especially with an outside rural crime scene.
You're right IMO about whether LE has enough biological material to yield a decent sample, absolutely. Ditto "being not related"--absolutely possible. But one more way DNA evidence has possibly not been helpful ("hasn't panned out") is if there simply isn't anything to compare any CS DNA to. And I think that's a very significant possibility.
The other week we discussed how perhaps as many as 50 million Americans (at an estimate) may have sent DNA in to one of the commercial DNA companies. Yemelyan very helpfully discussed how different testing protocols might limit the use of any of that DNA information, but we also need to realize that even the commercial DNA samples can't automatically be searched, not legally. As I understand it, people who submit samples must specifically opt-in to have that data copied to a searchable database. So just submitting DNA to "123 and me" apparently doesn't make your DNA searchable, you must also give informed and explicit consent for that ahead of time. And there are reasons to be concerned about the accuracy of the testing to begin with. (1.)
I tried a search just now and various articles say perhaps 50-75% of Americans might be at least partially linked to DNA from related samples that have been submitted--and the articles specify they mean white Anglo Americans. I'd suggest you search this if you're interested; I only took a short look at this and there's a lot of variation in the numbers. But one source that was particularly interesting is a Pew Research article,
About half of Americans are OK with DNA testing companies sharing user data with law enforcement , that says around 35% of people surveyed did not approve of DNA information being searchable by lawn forcement.
Now I'm just guessing, strictly uninformed guessing, but I'd guess maybe 95% of people in Salt Lake City would approve of their DNA data being searchable. Geneology is important to many Mormons and they're law-abiding people.
But go to the Mississippi Delta, where a third of residents live below the poverty level (NBC News), or Idaho, where fewer than 45% of residents have covid vaccinations (vs 15% for the general population, source US Census.) IMHO in general, these people do not trust science or central government, and many/most of them IMO are not going to opt-in to have their DNA searchable--most of them won't send their own DNA and neither will many/most of their relatives IMO. Incorrect DNA test results are IMO a significant risk.
So just "having DNA from the crime scene"
*might* turn out to be useful in prosecution of a subject, possibly in identifying a subject for arrest. But even if LE has an excellent quality DNA sample and they feel sure it is from the killer, there is still an unknown but clearly significant chance it will be of no use (2.)
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1.) Tandy-Connor, S., Guiltinan, J., Krempely, K. et al. False-positive results released by direct-to-consumer genetic tests highlight the importance of clinical confirmation testing for appropriate patient care
. Genet Med 20, 1515–1521 (2018). Redirecting
Genetic Tests and ‘False Positives’
J Forensic Sci; 2003 Jan;48(1):47-54. "How the probability of a false positive affects the value of DNA evidence"
2.) The numbers are a guess; a web search will let you get your own set of numbers. The number of samples submitted, and how many of them can legally be used for searches, and how much of the related population is affected, and many other specifics--all of these vary by news article.
