LAWRENCE — Investigators want to interview every worker and contractor who entered the former Millennium nightclub building where the fire started that wiped out nearly an entire city block of mostly multifamily buildings.

“Obviously, we need to know what people have been in there,” police Chief John Romero said yesterday of trying to find the cause of the blaze that forced about 200 people to flee their homes into the brutal cold Monday morning.

Interviews are underway with “electrical, stucco, plumbing and drywalling” contractors who worked at 34-44 Parker St., which was being renovated into a restaurant, Romero said.

Fire Chief Peter Takvorian said the interviews will most likely last through the weekend.

Officials have called the fire “suspicious” but have never said they believe the cause was arson.

An illegal propane heater was found at the building on Friday before the fire. A year ago, a fire investigator deemed the property an “extreme hazard” after workers on the site were caught burning scrap wood in a 55-gallon drum for heat. Illegal space heaters and cans of kerosene and propane were also strewn about, prompting firefighters to post a large X on the building indicating it was unsafe to enter in the event of a fire.

A task force of local police and firefighters, state troopers and Alcohol Tobacco and Firearms agents sifted through rubble yesterday looking for clues. However, Romero said it was difficult because the building had “burned right down to the foundation.”

Among those being interviewed is Alexandra Santos of MAR Environmental, who is listed as the general contractor on a building permit issued for 34-44 Parker St. in November. As the general contractor, Santos would oversee subcontractors working on the project.

Santos did not return several messages left on her work and cell phones.

Building owner Geraldo Torres said on Tuesday that in the past he employed his own construction crew to build the condominiums or duplexes he has developed around Lawrence. But with this project, he was using subcontractors while he and his wife, Nereyda Trempe, also functioned as general contractors.

Torres said Tuesday that he had spoken with many of the subcontractors because they lost tools and equipment in the fire. Their electrician, Louis Daniel Arroyo of Springfield, lost ladders, tools and recessed lighting fixtures that were going to be used in the restaurant, while their stucco contractor, Joe Delacruz, also lost some items.

The building has been the target of thieves in the past; it was broken into twice over the past year.

On Jan. 19, 2007, Torres reported an air conditioning unit and 24 feet of scaffolding stolen. There were no suspects or witnesses, according to a police report.

Then, in August, Torres reported numerous tools stolen from the building, including a Mitre saw, radial arm saw and portable compressor. An investigation revealed someone got into the building through a basement window and then cut a lock and cable that was securing all the tools together.

“This building, for all intents and purposes, is not very secure,” Patrolman David Augusta Jr. wrote in a report last summer. “There are several areas where you can see daylight through the walls. On the second floor, pigeons can get inside through small openings in the walls.”

Augusta advised Torres to store valuables elsewhere “until the building could be made more secure.” He also offered to make extra late-night checks on the property.

More recently, Torres and Trempe said the building was very secure, with two deadbolts on the front door and the other two doors on the first floor sealed up tight. The only access, he said, was through a second-floor window that had been removed so that a brace could be installed to hold up the scaffolding on the side of the building.

“It was very hard to get in,” he said, noting that someone would have had to climb 14 feet up the scaffolding and through the open window. “Somebody had to break in to start the fire.”

He also said that the electrician turned off the power to the building at the main breaker box in the basement every night before leaving the construction site.

Trempe and Torres had planned on opening a 110-seat restaurant, the Outside Restaurant and Lounge, on the first floor, and developing four apartments on the second and third floors. The couple did not have fire insurance on the property although the terms of their construction loan required it.

Utility crews worked at the scene yesterday and by day’s end, both electric and telephone service was restored to the area, according to spokespersons for National Grid and Verizon.

Staff reporter Jill Harmacinski can be reached at 978-946-2209 or by e-mail at JHarmacinski@eagletribune.com.