Getting your DNA tested
For the better part of this century, direct-to-consumer DNA testing has been available. The procedure is simple, spitting into a tube, and can be done at home, and the sample mailed to the company (mostly in the USA). The two main threads of the analysis have been (1) testing of medically relevant genes, and (2) determining ancestry. Some millions of people around the world have done this, and many have discovered relatives they didn't know they had.
In 2010, a small (2-man) company in Florida was set up to help "amateur and professional researchers and genealogists," including adoptees searching for birth parents. People could choose to upload their DNA from whichever direct-to-consumer company they had used. More recently, this capacity was adjusted so that unknown DNA samples from crime scenes could be matched to (typically distant) relatives. These relatives could then be the starting point to track back up through the family tree, to identify their ancestors; and then track back down through the generations to see if there's a plausible suspect amongst the descendants. This approach has been successful in apprehending a small number of "cold case" criminals, perhaps the most notable of which is the "Golden State Killer", a former policeman who had committed many burglaries, rapes, and murders in California the 1970s-80s. This approach could be, but is not (yet), used in New Zealand.
This family tracking to find criminals is not without controversy.