Three months after his bone marrow transplant, Chris Long of Reno, Nev., learned that the DNA in his blood had changed. It had all been replaced by the DNA of his donor, a German man he had exchanged just a handful of messages with.
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Mr. Long had become a chimera, the technical term for the rare person with two sets of DNA. … Doctors and forensic scientists have long known that certain medical procedures turn people into chimeras, but where exactly a donor’s DNA shows up — beyond blood — has rarely been studied with criminal applications in mind.
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The assumption among criminal investigators as they gather DNA evidence from a crime scene is that each victim and each perpetrator leaves behind a single identifying code — not two, including that of a fellow who is 10 years younger and lives thousands of miles away.
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If another patient responded similarly to a transplant and that person went on to commit a crime, it could mislead investigators, said Brittney Chilton, a criminalist at the Sheriff’s Office forensic science division.
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Everyone who has reviewed Mr. Long’s case agrees on one thing: … it’s impossible to say how many other people respond to bone marrow transplants the same way he did.
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