Unfortunately your understanding, and that of nearly every juror in the US, is wrong. Tainted by the pro-police television narrative, that cops never mess up and that all crimes can be solved with the application of Forensic Science™. The link I provided elaborates further, but one reason from the concerningly long list: DNA testing really is little more than circumstantial evidence - it’s ridiculously easy for your DNA to show up at the scene of a crime you were not involved with. In general, it’s more precise than blood splatter or ballistic analyses, but not nearly by the margin you think.
Unfortunately your understanding, and that of nearly every juror in the US, is wrong. Tainted by the pro-police television narrative, that cops never mess up and that all crimes can be solved with the application of Forensic Science™. The link I provided elaborates further, but one reason from the concerningly long list: DNA testing really is little more than circumstantial evidence - it’s ridiculously easy for your DNA to show up at the scene of a crime you were not involved with. In general, it’s more precise than blood splatter or ballistic analyses, but not nearly by the margin you think.