Several days after a 15-foot steel pipe plunged off the Deutsche Bank building, federal authorities said Monday that they will expand their probe into the building's demolition.

The Occupational Safety and Health Administration says they will look into the "means and methods" of the demolition project which allowed the pipe to fall 35 stories and through the roof of a nearby firehouse.

A stop work order has been in effect since the incident last Thursday.

Demolition of the 40-story building had been delayed until late last year because of potential environmental damage.

In the last month, one worker has fallen down an elevator shaft at the site and two others have fallen off scaffolding.

Residents had been complaining for weeks about other objects falling off the building. Nancy Keegan, who lives next-door, said she was walking her dog last month when she glanced up to see a 6-foot chunk of wire mesh falling from the tower onto a street lamp.

"It's really scary," she said.

The state agency that owns the building, the Empire State Development Corp., has refused to comment on the cause of the pipe mishap.

But Dave Newman, director of nonprofit New York Committee for Occupational Safety & Health, worried that the demolition contractor was cutting corners.

John Galt Co. must complete demolition by year's end or face financial penalties.

"It's clear that whatever oversight is in place," Newman said, "they've had warnings about this and it's not adequate."

The company, which did not return calls for comment, was cited by OSHA after one worker fell 40 feet and other workers removed asbestos without proper respiratory equipment.