The problem with using DNA to identify someone in crime is that we leave DNA everywhere. See this case for example: https://www.wired.com/story/dna-transfer-framed-murder/
DNA transference, law enforcement access to large DNA databases, familial matching, and advances in extracting DNA from trace samples make for a scary combination. Lukis Anderson was damned lucky that the person who inadvertently transferred his DNA to a crime scene could be identified.
Is there an oracle that will tell you who committed the crime? No. But it seems odd to be OK with some forms of evidence that are even more unreliable than this, if your issue is about reliability.