THE NEW YORK CITY MEDICAL EXAMINER’S OFFICE WAS LOCATED IN a nondescript, six-story white brick building in Kips Bay on East Twenty-Sixth Street and First Avenue. If offices had occupied the top two floors they would have offered views of the East River and the north end of Brooklyn. But the upper floors were not meant for the scientists and doctors who roamed the building. They were instead reserved for water and air purification systems. The circulated air within the world’s largest crime lab was clean, pure, and dry. Very, very dry. Humidity was bad for DNA, and DNA extraction was one of the crime lab’s fortes.

In the cold, damp basement was the bone-processing laboratory. A technician opened the airtight seal of the cryo tank, releasing liquid nitrogen fog into the air. A triple layer of latex gloves protected the technician’s hands. His face was safe behind a plastic shield. He reached into the tank with a pair of forceps and lifted the test tube from the fog. It was filled with white powder that had minutes earlier been a small bone fragment specimen. The liquid nitrogen had been used to freeze the bone, and then the frozen specimen was shaken violently in the bulletproof test tube. The result was total pulverization of the original bone sample into a fine powder. The technique allowed scientists to access the innermost portion of the bone, which made the chance of extracting usable DNA more likely. The concept was remarkably simple and had been developed based on two of the basic concepts of physics—the law of motion, and thermodynamics. If an apple were thrown at a wall, it would break into many pieces. But if the same apple were frozen solid by liquid nitrogen and then hurled at the wall, it would shatter into millions of pieces. When it came to extracting DNA from bone, the more pieces the bone could be broken into, the better. The finer the powder, better still.

The tech placed the test tube into a rack with a dozen others containing pulverized bone. With the nitrogen fog still spiraling from the latest tube, he dipped a titrating syringe into a beaker of fluid, drew ten cc’s into the chamber, and added the extraction products to the pulverized bone. The next day, instead of bone powder, a pink liquid would fill the tubes. It was from this liquid that a genetic code would be procured—a sequence of twenty-three numbers unique to every human on the planet. Their DNA profile.