Michael A. Schwartz, attorney for the family that owns the property, declined to comment Tuesday, but said his clients were cooperating with the District Attorney's Office.
Nutter said all city agencies will cooperate with the investigation and that the city was conducting its own internal probe. The tragedy of the Kensington fire, he said, presents a chance to "send a message" to other property owners that they must take responsibility for making their buildings safe.
An investigation into the cause of the fire is pending. Fire Commissioner Lloyd Ayers said all future findings in the case will go to the grand jury.
Bill Gault, president of Local 22, International Association of Fire Fighters, applauded the decision and lashed out at "the absentee landlord who allowed the warehouse to become a death trap."
"We lost two of our own and we'll never get them back," Gault said in an emailed statement. "We can, however, send a zero-tolerance message to these reckless landlords that we're coming after you and holding you criminally responsible for your willful negligence in the hopes that a tragedy of this magnitude never happens again."
The five-alarm fire at the former mill erupted in the early-morning hours of April 9, and spread quickly as winds whipped the flames into an inferno. Philadelphia Fire Lt. Robert Neary and Firefighter Daniel Sweeney were killed when a wall collapsed in an adjoining furniture store.
The owners of the Buck building, brothers Michael, Nahman and Yechiel Lichtenstein of New York, had been cited three times since November by the Department of Licenses & Inspection for failure to secure the property against vandals and squatters.
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