Many nations have public gene banks. These banks contain many indigenous organisms' gene sequences as well as anonymized gene sequences from people from their respective countries, which is used for national and international medical research. These gene banks exchange information regularly. One of the most public ones is US' own NIH GenBank [0].
A small search surfaces a lot of gene banks which store human and non-human DNA. Use your favorite search engine for this.
Generally submissions are done with patients' consent, but I'm not very sure that some of the blood samples are directed to national private databases for countries' own use and research.
The reasons doesn't have to be nefarious. Knowing your population's genetic weaknesses is a good way to defend it, and having access to a wide pool allows a deeper understanding of genetic conditions and how genetic therapies are working.
Also, earlier comments than mine already cited how law enforcement in US is already using this as evidence.
I'm an ordinary person. I don't have access to more information than you do.
[0]: https://www.ncbi.nlm.nih.gov/genbank/