That number is routinely called The Prosecutor's Fallacy (in regards to DNA).
The State of North Carolina goes to trial against Donnie Defendant, who is alleged to be the infamous “Tarheel State Killer” and charged with committing a
nccriminallaw.sog.unc.edu
I think these articles will be helpful in starting to understand why the interpretation of that number is completely and totally wrong.
This article explains Baye's Theorem:
Let’s set the scene. You’re driving alone at night along an empty road through the woods. It’s rumoured to be haunted, but you’re not particularly scared – you don’t believe in ghosts anyway.…
tomrocksmaths.com
This article explains the Prosecutor's Fallacy:
Picture the scene. You’re a homicide detective on one of those ‘CSI-type’ shows. You’ve found a DNA sample left at the crime scene, but no other evidence to try and find your suspect. You decide to…
tomrocksmaths.com
However, those are just the beginning. I would recommend reading the 4 classic books by Edward R Tufte. These are fundamental to detecting and understanding statistical lies. These books are well-written and eye-opening. You will NEVER look at numbers and graphs the same way again. IF you are an attorney, you especially need those books. I think you will find them incredibly helpful and use them frequently, not just for work, but for all aspects of life. They are that important and life-changing.
The sheath was made of leather. There should have been bovine DNA on it. Humans and bovines share 80% of their DNA. How would someone clean bovine DNA off leather without any evidence of cleaning solvents? Also, it is not believable that this hand made item had no DNA from the person who cut, sewed and finished it, not under the threads, in the seams, under either part of the snap - obviously something is very, very wrong.