A focus of the investigation is the weight of the 50 vehicles parked on the roof and the age of the building, which was built in 1925.
The garage had dozens of violations dating back decades. Four of those violations are still open.
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The Manhattan district attorney's office will investigate the collapse of the Ann St. parking garage, a spokeswoman for the office confirmed on Wednesday.
The building first started to be used as a parking structure in 1957 and the owner has been issued dozens of violations since.
Four of those violations are still open and have not been resolved - even though they were issued years ago.
They range from not having a proper fire exit in a stairwell back in 2013 to another for having broken and defective stairs in 2009. The list also includes a violation for having defective exit lighting in 2003.
And that same year, the building owner was cited for missing concrete on the steel beams on the first floor and exposed rear cracks. That violation from 20 years ago is still listed as open.
The building department's website does not specify whether the owner filed a certificate of correction with the department, which the owner was required to do.
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In all four cases, city records show the owner paid the fines - a total of $2,500, but the DOB website does not detail whether the violations were ever corrected.
Two additional open violations are for non-safety related defects found during periodic elevator inspections, the department said. It's unclear whether any of the violations contributed to the collapse.
Just last year New York City strengthened its code around parking garage inspections.
"The City Council passed a law that stated that the obligation to do these inspections through an engineer must be carried out by the owners of the property," Mayor Eric Adams said. "It's the law, they have to abide by the law and there's an investigation into exactly what happened here."
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Another question is whether or not the century-old design could have anticipated a roof full of cars.
Bryan Levi posted a picture on Reddit about a year ago showing the cars on the roof.
Was collapsed parking garage built to withstand roof full of cars?
"I just think it looked a bit ridiculous, I don't post much on Reddit but I thought that people who didn't live in New York might find it humorous, find it ridiculous just how many cars were parked up there," he said.
Comments on the post questioned whether or not the rood could sustain the weight of all those cars.
In the 1920's, a Ford Model T weighed about 1,800 pounds. By the 1950's, some cars weighed as much as 5,000 pounds. Now it's not uncommon for an SUV to weigh 6,000 pounds or more.
Muhammad Rahal is an engineer.
"The question is more whether the floors are designed for that loading and whether they are deteriorated to the point that they can't withstand that load anymore," he said.
Rahal says investigators will be able to tell by looking at the thickness of the beams and how the concrete slabs were reinforced if the roof should have been holding so many heavy cars, or if it was designed to hold cars at all.
The New York City Fire Department is slowly and methodically taking down the building.
Meanwhile, crews are starting with removing the cars then they will deconstruct the building.
More than 50 cars were parked on the roof, which collapsed into the rest of the structure. Gas tanks and electric vehicles in the debris are also complicating the deconstruction process.
"Right now we are transitioning to how we safely take down that building and it is incredibly complex," Commissioner of NYC Emergency Management Zach Iscol said. "There are over 50 cars on the roof, the building is not structurally sound, you think about hazardous materials that are in that garage, gas tanks, fluids, further complicated by the fact that there are potentially electric vehicles in that garage."
Multiple agencies including DOB, HPD, NYCOEM, NYPD, FDNY, MTA and others are working together to safely demolish the building and remove the vehicles.
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Seven patients were treated at New York Presbyterian Hospital Downtown and Bellevue Hospital. The FDNY said it appears most of the the patients were treated and released.
The deceased garage worker, the 59-year-old manager, was removed from the rubble later Wednesday.
NYC parking garage collapse: What cleanup crews have to contend with
NYC parking garage collapse: What cleanup crews have to contend with
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