One catchphrase is "means, motive, opportunity". DNA can indicate a possible opportunity, in that a suspect's DNA can be shown to have appeared in the same plac

One catchphrase is "means, motive, opportunity". DNA can indicate a possible opportunity, in that a suspect's DNA can be shown to have appeared in the same place a crime occurred. That doesn't address means or motive, i.e. whether the suspect had the ability or inclination to commit the crime. If I were on a jury and a DNA sample was all the prosecution had, my verdict would be not guilty. Keeping a massive DNA database and using it to convict someone, anyone because a crime occurred near something they touched before would be fallacious and unjust. However, if we already had other reasons to suspect someone, and DNA gives us another, that's much more powerful.