This is inspired on a story in a TV show: The police have the DNA of an unknown murderer X. Search of DNA records finds a person A who is most likely a close relative of the murderer (but totally innocent himself). Based on this result, the police finds the criminal X. It turns out that A's DNA should not have been in the system, and A's rights have been violated.
Can X claim that the evidence should be inadmissible because A's rights were violated? (In the TV show he claimed so successfully, which I found dubious).
(I think a real case was the Unabomber, where on one of his letters the police found the finger print of a copy store employee who had sold copier paper to the Unabomber).