While debates rage about why more buildings have not gone up at the World Trade Center site, there is one, shrouded in a web of black netting and full of trade center dust, that can't seem to come down.

The vacant 41-story former Deutsche Bank AG building looms above ground zero, contaminated with toxic waste and still holding tiny body parts more than four years after the trade center collapsed onto it on Sept. 11, 2001. Removing it from the landscape has become a more challenging task than cleaning up the twin towers.

"That's more or less a vertical Superfund site, and we're living right next to it," said neighborhood resident Esther Regelson, referring to a federal program for cleaning up the nation's most polluted industrial sites. She is concerned that taking down the building improperly will contaminate the area even more.

The eyesore presents different problems for a business district struggling to coax companies back to office space destroyed by terrorists. The first rebuilt skyscraper near ground zero, 7 World Trade Center, opened Tuesday with less than one-fifth of its space rented.

"Having it still there isn't helping," said Eric Deutch, president of the Alliance for Downtown New York.

Development officials hope to bring down the building over the next year, making way for a new tower that could offer apartments or a hotel. But the cleanup that began last fall has stalled repeatedly as the Environmental Protection Agency and other regulators cited contractors for violations.

Construction workers, helped by the Fire Department, have another, wrenching task as they sift through debris. They have recovered more than 600 tiny bone fragments so far that had not been found in searches of the building shortly after the attacks.

Family groups and four U.S. senators have asked for more thorough sweeps of the area to search for other fragments.

"It would be very foolish for us to think that that's the only building that had remains on it," said Diane Horning, who lost her son at the trade center.

Before the cleanup began, the 32-year-old building was embroiled in a legal battle between the company, insurers and the government over who was responsible for it.

The tower lay untouched for months after the collapsing south tower tore into it, leaving a 15-story gash in its facade. The building became infested with mold caused by moisture from fire sprinklers and also contains asbestos, lead, mercury and toxic dust from the trade center.

Deutsche Bank got into court battles with several insurers for payments to help take the building down. It also sued the city for more than $500 million in damages to the tower.

The Lower Manhattan Development Corp., the state agency overseeing rebuilding at ground zero, bought the tower for $90 million two years ago after "the private sector was unable to create a solution," agency President Stefan Pryor said.

It took another year to begin the cleanup because the agency needed the EPA and others to approve one of the most complex demolition plans in the city's history.

The LMDC hopes to begin dismantling the building from the top down next month. Once it is gone, in a year or so, officials plan to build the last of five proposed towers to replace the trade center there. Planners may develop it into an apartment complex or hotel.

The cleanup, which began in September, caused immediate controversy when several bone fragments were found on the building's roof. In recent months, hundreds more were found. Family members of Sept. 11 victims, many of whom never recovered remains of their loved ones, were outraged.

Sen. Charles Schumer became the first of four senators to ask the Defense Department to send a specialized military unit — best known for finding MIAs in Vietnam — to search the area for remains. The Defense Department is open to sending the elite unit, Schumer said, and "we hope the city will allow them."

At a state hearing on Thursday, Pryor and Deputy Mayor Daniel Doctoroff said the LMDC and city team are doing a thorough job searching and do not need help.

The search for remains, though, was suspended weeks ago after the EPA found that construction workers were sifting for the remains in an asbestos-contaminated area without proper protection. The agency also halted cleanup work for a few days this month after witnessing a contractor taking out debris that had not been thoroughly cleaned.

LMDC spokesman John Gallagher said the agency asked regulators to keep better tabs on the situation to ensure that the cleanup was being properly handled.

EPA spokeswoman Mary Mears said the violation was part of a "pattern" with the cleanup, the fourth problem of its kind in recent weeks. The EPA has questioned the use of a chute to send down debris and other aspects of the cleanup. After shutting down most cleanup work for more than a week, the EPA allowed contractors to begin removing debris from the building on Tuesday.

The Occupational Safety and Health Administration and state labor officials have also cited contractors for several violations this year, including an incident in which an employee fell 30 feet in March while building part of a sidewalk canopy system without a harness.

Regelson, who lives directly behind the Deutsche Bank building, said the tower "pretty much saved our lives" on Sept. 11 because it shielded her residence from the south tower's collapse. But then her asthma worsened, and she developed an acid-reflux problem.

She worries now that taking down the building will spew more pollutants into the air. She is saddened by the discovery of human remains, but said the toxic dust inside the building is more harmful.

"The body parts aren't going to kill me," she said.