New York ? More human remains from the collapse of the World Trade Center towers have been found by construction workers repairing nearby buildings almost a year after the terrorist attack.

Workers found three human bone fragments the size of small twigs on the roof of a heavily damaged 40-story building just south of ground zero, according to Port Authority Police Lt. John Ryan, who oversaw remains recovery during the nine-month excavation of the site.

Black netting and a large American flag shroud the Deutsche Bank tower, left, adjacent to the World Trade Center site. Police said construction workers on the roof of the badly damaged building found three bone fragments Wednesday.

Earlier this month, workers spotted a woman’s pelvic bone atop a 25-story building at the southwest edge of the trade center site.

Ryan said other fragments have been found in recent weeks.

“When you think about all the tons of debris and the force of the impact, even though everything was thoroughly checked and rechecked, you’re going to have situations where remains will be found,” Ryan said.

After the excavation of the 16-acre site ended in June, firefighters and police officers expanded the recovery effort to several nearby buildings. They have found bone fragments, teeth and even parts of an airplane luggage rack.

City officials had said the more thorough inspections were delayed because the work at the trade center site blocked access to the buildings, and some had to be secured before crews could enter.

The Deutsche Bank building, where the bones were found Wednesday, was the last to be searched.

“While they were searched thoroughly, some of the damage may have precluded people getting to every inch of it,” Ryan said. “Now that it’s being repaired or those damaged areas are being removed, they’re finding things.”