OK. DNA that we are talking about is not a tiny strand under a microscope. For DNA testing, it is extracted from nucleated cells. To get DNA, you have to have source of nucleated cells - blood, saliva, epithelium of the oral mucosa, sweat if it contains shed skin cells, hair roots. Seldom would touch DNA come from just one cell; “touch” like a fingerprint contains shed epithelial cells, sweat and sebum (another potential source of DNA).
So if you use biometrics on your phone, you can leave DNA on the screen. Theoretically, someone who doesn’t like you can take your cell phone (not touching the screen) and rub the screen against something (including the button of the sheath) where people want to leave your incriminating DNA. They can steal your worn T-shirt and rub the collar against the same button of the sheath.
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So I made notes. It was a little bit strange after that to not hear anbout any murderer’s DNA on the crime scene but, the case was closed.
But, if you subscribe to the theory, it is hard to let go. If DNA can be even transferred from one person to another and they are not in direct contact, which I btw, fully believe can happen, then the same fact could be used as a counter argument against “BK’s touch DNA on a sheath button irrefutably proves that he was the killer.” Maybe there will be a wealth of another information during the trial - as I have said, I am split about “BK’s the killer” theory but not against it. If anything, I just can’t believe that he worked alone, that’s all. But…maybe.
Mostly, you just can’t ardently persuade the public why touch DNA is irrelevant in one case and then assume they will forget, you know?