Quite correct on the guidelines; my error. I don't know about the statistical independence of the DNA search and the match on separately-collected DNA directly

Quite correct on the guidelines; my error. I don't know about the statistical independence of the DNA search and the match on separately-collected DNA directly from the suspect (once a suspect was found via the DNA search), but I think it's a little irrelevant; as long as existing laws aren't broken, I understand the court to generally not care how police became aware of evidence of a crime. Consider the oft-maligned "Stopped for a broken tail-light but there were drugs in the car" scenario. If the defendant goes to trial for the drug possession, the broken tail-light doesn't enter into the trial as evidence (mention of it may enter if someone asks the arresting officer why they chose to stop the defendant). Bringing the analogy around to this case: if a DNA relative match narrowed the field of suspects to the relatives of match candidate X, then the police still need evidence tying relative Y directly to the crime. In this case, they subsequently investigated Y and found such evidence. Should the initial scan of a DNA database for candidate X have been illegal? I think that's an open question. I personally don't think it should be.