The “Golden State Killer (GSK)," aka, the "East Bay Rapist", Joseph James DeAngelo was arrested last week for 12 murders and 50 rapes in the 1970's and 80's. The arrest raised 4th Amendment concerns about law enforcement's right to search DNA datasets for suspects in crimes.
When a family member seeks to learn about their own DNA and sends a sample to a commercial activity, they are indirectly creating legal jeopardy for a relative engaged in criminal activity if a DNA sample were left at a crime scene. The crime scene DNA could be linked to the relative as having a familial tie via open source or commercial datasets, potentially limiting the number of suspects to those in a family line.
Do unreasonable search and seizure protections apply? The 4th Amendment protects against searches done by the government that are deemed unreasonable under the law, but not all searches are considered unreasonable. Like an eyewitness statement, artist depiction, or a traffic camera capturing the license plate of a suspect, the information is only useful when used with other data to provide an identification. DNA left at a crime scene should similarly serve as a catalyst for relational matching against databases.
Using DNA datasets to match against crime scene DNA is consistent with other uses of data, and the victims and public good are best served by allowing DNA data searches.