Remains of the Day

In New York, efforts to identify the terrorists were more difficult. There were still too many victims who had not been identified by their DNA, making it impossible to flag the terrorists by a process of elimination. The scientists needed the DNA profiles from the hijackers. Shaler's office turned to the FBI for help. The request made its way to the desk of Alan Giusti, the lab's forensic examiner in charge of the September 11 investigation. As it turned out, Giusti had worked for Shaler at a private DNA lab in the '80s, when the technology was in its infancy. Now Giusti was spending his days using genetic clues to nail bank robbers and murderers.

Working with a team of specialists on the third floor of the J. Edgar Hoover building in Washington, D.C., Giusti was in fact already creating DNA profiles of the New York terrorists from scraps of evidence left behind in hotel rooms and rental cars in the days before the attacks. A large basement room in the FBI building was filled with boxes of evidence, each piece stored in a brown paper bag. "It looks low tech," says Giusti, but the bags keep out humidity or dryness—"the two demons of DNA analysis." For DNA sleuths used to working with tiny scraps of genetic material, it was the mother lode: "fingernail clippings, chewing gum, hairbrushes, anything we could get dead skin off of," he says. When they swabbed the "friction areas" along the inside collars of shirts, the DNA came back mixed, an indication that the hijackers may have shared clothes. A few pieces of used tissue, tossed into a hotel room wastebasket, yielded clues, as did saliva from cigarette butts. Giusti mixed them with enzymes to release DNA—"like cracking the nut of a shell to get the meat out," he says. The "amplified" product—a few drops of clear, viscous liquid—was then put into a large machine that spits out lists of numbers, a genetic map unique to each individual.

It took more than a year for Giusti's lab to get back to New York with the results—a single page with 10 genetic codes. It was February 2003, and Shaler and his crew got to work on the numbers immediately. They were anxious to see if they could make a match to any of the unidentified remains they had retrieved. Shaler's deputy, Howard Baum, thought it would never work. How could they be sure that the clothing and tissues and cigarette butts were really those of the hijackers? "We had no idea where the profiles came from or how they were developed," says Baum. "I was skeptical." A scientist entered the codes into the lab's Mass Fatality Identification System. They told the computer to display any matches to the hijacker profiles in red. Immediately, there were two matches. Shaler and Baum were elated—they would be able to weed out at least some of the terrorists' remains after all. "Finding the first match was the big deal," says Baum. "It was proof of the concept—that we could identify the hijackers. Our job was not for the dead, it was for the living."

The red-flagged fragments "have been removed from the general population" of remains, says Ellen Borakove, spokeswoman for the New York medical examiner's office. "We will not discuss where they are."

Shaler and the other New York pathologists sent some of the most damaged human fragments to private forensics labs that specialize in advanced DNA-retrieval techniques. One was the Bode lab in Lorton, Va., which is known for extracting genetic material from bones. The New York team gave the lab a seemingly impossible challenge: to identify 12,000 burnt bone fragments. The bones "had been burning in the rubble at extreme temperatures," says Mike Cariola, the lab's director, "and we were only getting DNA samples on half the ones we tested." Cariola recalls that "some pieces of bone were so charred that if you held it with two fingers it would disintegrate." But using a new technique they developed that releases genetic material by removing calcium from bones, Cariola and his colleagues were able to get DNA profiles out of 2,000 samples that were previously unreadable. Cariola says the work resulted in at least 18 new identifications.

In September 2007 the medical examiner's office in New York announced it had identified a fourth set of terrorist remains —the 13th identified to date.