Ancestry/Genealogy

By making connections between relatives, a good sleuth could construct a family tree and then conduct more targeted research that might lead to someone who had never submitted his or her DNA for testing, as was the case with the Golden State Killer.

“Think of your family like layers of an onion,” Erlich tells Paul Raeburn of Scientific American, with each layer from the center of the onion representing increasingly distant relatives. “When you go to very distant relatives, chances of a link are much higher.”

The researchers estimate that within two or three years, as more and more people submit their genetic data to genealogical databases, 90 percent of people who hail from European ancestry will be traceable in this way, reports the New York Times’ Heather Murphy.