The construction contractor under investigation for a fatal fire in the former Deutsche Bank building is facing increased scrutiny after a construction worker died yesterday in an accident at another of its construction sites.

The company, Bovis Lend Lease, was ordered to halt work on the Trump SoHo Hotel Condominium building at 246 Spring St. after the man plummeted 42 stories to his death yesterday afternoon when a portion of the top floor collapsed just before 2 p.m.

The Department of Buildings commissioner, Patricia Lancaster, called the accident “clearly unacceptable,” noting that the project had already accrued 11 other safety violations.

One possible violation that will be decided at a hearing this month is operation of a crane in an unsafe manner, and witnesses yesterday said they saw the crane swinging its load erratically in the moments before the accident.

Officials said the preliminary investigation had ruled out the crane as a cause of the accident, however, blaming weak wooden molds on the top floor. Ms. Lancaster said the wood forms had given way under the weight of wet concrete as it was being poured from above.

The worker who died had been tamping down the concrete to push out air bubbles alongside other laborers, officials said. He was flung beyond the safety nets extending from the 40th floor and fell into an alley at street level, officials said.

Police said they could not identify the man yesterday evening because he was carrying no identification. They were searching for family members who may live in Brooklyn. Others working at the site said the deceased worker was a Ukrainian immigrant, but did not know his full name.

Police said the man’s body had been split in half during the fall. Bovis Lend Lease said in a statement sent by e-mail that it was in the process of conducting its own internal investigation of Difama Concrete, the concrete subcontractor that employed the worker. A message left for the Brooklyn-based Difama Concrete last night was not immediately returned. A representative for developer Donald Trump referred calls to Bovis Lend Lease.

Another worker was also thrown off the side of the building during the collapse, but was caught by the nets. After the fire department arrived on the scene, a debris bin was lowered down using a crane to rescue him, officials and workers said.

“He was buried in concrete up to his neck,” one worker who witnessed the collapse, Walter Brown, said. “We had to think quick and use the box.”

The second worker was in critical condition after the fall, but his injuries were not life threatening, officials said. Two others were also treated for minor injuries at the scene, according to fire officials.

Bovis Lend Lease is currently being investigated by the Manhattan district attorney’s office for its role in a fire at the former Deutsche Bank building in August that left two firefighters dead. There were also numerous safety violations at that site before the fatal fire.

The Trump building has faced opposition from neighborhood groups, including the SoHo Alliance, which submitted a legal appeal in the fall to stop work on the building. It said the developers, which include Mr. Trump and the Bayrock/Sapir Development Group, skirted zoning laws in obtaining the permits for the building and have hurried the project along too rapidly.

Construction workers had managed to erect 42 of the 46 stories planned for the building since the project began in May. The building had been slated for completion in the spring of 2009.

“We have a construction company that has many complaints about their construction methods, and this is just another example,” the director of the SoHo Alliance, Sean Sweeney, said, referring to the former Deutsche Bank building. “If they took some time maybe this man would be alive today.”

Fire officials said blocks around the building would be closed off as the building was shored up to prevent debris from falling. Ms. Lancaster said construction would not continue, however, until Bovis Lend Lease developed a safety plan.

The construction company was also cited yesterday in the aftermath of the accident for not maintaining adequate fire extinguishers or a fire escape hatch.