CNN  — 

The remains of a man killed during the Sept. 11 terror attack in New York have been identified 17 years later.

The New York medical examiners’ office on Wednesday identified the victim as Scott Michael Johnson, 26, who worked at an investment banking company at the World Trade Center.

Johnson is the 1,642 person to be officially identified in the Sept. 11, 2001, terror attacks that left nearly 3,000 people dead. He was identified after his DNA was re-tested using a new and improved technique, Chief Medical Examiner Barbara Sampson said in a statement.

“In 2001, we made a commitment to the families of victims that we would do whatever it takes, for as long as it takes, to identify their loved ones,” Sampson said. “This identification is the result of the tireless dedication of our staff to this ongoing mission.”

The medical examiner’s office received about 20,000 human remains, a majority of which did not include intact bodies or torsos. It has been working to identity the remains, some as small as a finger tip, primarily through DNA testing.

More than 1,100 victims remain unidentified, Sampson said.

During the attack nearly two decades ago, 19 men hijacked four US commercial airplanes and crashed them in New York City, Washington and outside of Shanksville, Pennsylvania, killing a total of 2,977 people.

Most of the remains are hard to identify because of the effects of heat and chemicals from the jet fuel. The new DNA system helps with testing of degraded samples, Sampson said.

CNN’s Joe Sutton contributed to this report