He had a leg up, he says, when he decided to pursue the idea of DNA databanks. He knew a lot of the right people. He had spent more than a year doing research in the labs at the Federal Bureau of Investigation’s training center at Quantico, Va., in the early 1990s. At the time, he was helping to develop ways to match DNA even when the sample was badly deteriorated — for instance, if it came from blood that had been sitting in the sun for a long time.

BUT in the evenings, he ate in the cafeteria with everyone else on the sprawling campus, including the many foreigners who had come to Quantico for training, people who would later became important figures in their own countries.

“They became ministers and police chiefs, and they kept inviting me to come consult,” he said. “So when I traveled I was talking to them about this, too.”

Some of the free tests are performed in Granada, some at the University of North Texas Health Science Center in Fort Worth, where his former boss at the F.B.I. lab, Bruce Budowle, is now the executive director of the Institute of Applied Genetics. Dr. Budowle says Dr. Lorente has a knack for pushing this particular agenda. “He is an excellent communicator who really excels at talking to the higher-level people,” Dr. Budowle said. “And he has the passion.”

Dr. Lorente says there is a real excitement to working on big-name cases like identifying the remains of Columbus and Bolívar. But it is the more intimate cases that stay with him longer.

“When you can look at a mother and you can say, ‘O.K., we have found your son’s body,’ ” he said, “that, for me, is huge.”

Dr. Lorente was born into a family of doctors and always loved science. The only question was what kind of doctor he would be. Then, when he was in medical school, a professor suggested that he write a paper on DNA analysis — in those days a brand-new area of research. He was hooked.