The National Institute of Standards and Technology has developed a tool to help scientists still struggling to identify the remains of about half the 2,800 people killed in the World Trade Center attack.

NIST, a federal agency, has devised a way to copy fragments of DNA using a method called the polymerase chain reaction, and it's created tools to amplify the fragments and make them eligible for analysis. The process is being applied to about 13,000 bone samples that haven't been identified.