(CNN) -- The remains of a firefighter killed in the September 11, 2001, terror attacks at the World Trade Center have been identified, the New York City Medical Examiner's office said Friday. Lt. Jeffrey P. Walz, 37, was identified after authorities retested remains that were recovered in the months following the attack. Of the 2,753 people killed in the attack, more than 1,100 people have not had remains identified, according to Barbara Sampson, acting chief medical examiner. More than 8,200 bone samples and additional samples require DNA testing, according to a report released by Sampson. Walz, who was last seen in the north tower of the World Trade Center, was survived by a wife and a son, according to an obituary in the Staten Island Advance. Crews finish installing World Trade Center spire .
Firefighter Jeffrey Walz was killed in the attack on the World Trade Center . Walz, 37, was last seen in the north tower . His remains were identified by city medical examiner's office .