Comment Re:System worked, then? (Score 4, Interesting) 163
So here we have a guy where there is nothing at all to tie him to the events except DNA match that is actually exculpatory in that its clear he isn't a match for the sample the Police believe is that of the perps; however it does indicate he may be a family member however distant. The police want to confirm this. Is it reasonable to "search" his blood to confirm the match, and is that than cause to search everyone one of his relations, and their offspring?
Your summary may be a bit too brief for the nuances here. It appears that the police found a partial DNA match with the suspect's father (in, remarkably, a privately-maintained - not state-controlled - DNA database), which in turn suggested that a close relative would be match. The police then examined publicly-available genealogy information to identify candidate relatives. From the genealogy records the police narrowed their search to three candidate individuals. Using various other circumstantial information they finally sought a warrant to collect a DNA sample from just one individual.
While I agree that there are legitimate "slippery-slope" concerns, based on the (admittedly brief) description in the linked article, it seems that in this particular instance reasonable steps were taken to minimize the scope and inconvenience (to potentially-innocent individuals) of the investigation. It wasn't a scattershot "We must test the DNA of all your male relatives!", but rather "We want to test the DNA of your one male relative whom we also suspect for reasons (a), (b), and (c)."