The method that identified DeAngelo will be used again. It has been used again, in dozens of cases. It will be used in cases not yet opened, against individuals not yet identified as suspects. The ethical and legal frameworks governing its use are still being built.
The case of the Golden State Killer is, in this sense, not finished. It is finished as a legal proceeding. As a question about how new technology reshapes what is possible in criminal investigations, and what constraints are appropriate on that reshaping, it continues to generate answers that the case itself did not settle.
A distant relative’s DNA helped expose Joseph James DeAngelo. It took months of genealogical work to follow that help to a specific name. It took an independent DNA comparison to confirm the name. It took a legal proceeding of unprecedented scale to produce a verdict. And it took the words of survivors, delivered over four days in August 2020, to make the legal proceeding mean what it meant to the people it was about.
All of those things were necessary. None of them, by itself, would have been sufficient.