UPDATED 12/22/11 9:35 a.m.

CHICAGO (CBS) — A memorial was held Thursday morning, one year to the day after two Chicago firefighters died when the roof of a South Shore neighborhood building collapsed in a fire.

As CBS 2’s Susanna Song reports, the commemoration comes as the owner of the building faces criminal charges.

LISTEN: WBBM Newsradio’s Mike Krauser reports

On Thursday morning, firefighters Edward Stringer, 47, and Corey Ankum, 34, were remembered by their comrades in the Fire Department at the scene of the deadly blaze last year. Fellow firefighters rang a bell in honor of the two brave men at the deadly site of the fire.

WBBM Newsradio’s Mike Krauser reports during the memorial gathering, Fire Commissioner Robert Hoff stood before a sea of firefighters in the rubble-strewn vacant lot, where the building at 1744 E. 75th St. where Stringer and Ankum died once stood.

Hoff said it was sacred ground, and it always will be.

“I want to thank everyone that was at the fire – every firefighter, paramedic that worked so hard to save firefighters’ lives,” he said. “I can truly say we did the best we could.”

Hoff asked those present to keep in their prayers the firefighters who worked at the scene, and Ankum and Stringer’s families.

Bells were rung for each of the fallen firefighters afterward.

The fire was largely out by the time Stringer and Ankum entered the vacant building, which had once housed the Banner Laundromat and Dry Cleaners. The firefighters had gone inside to look for homeless squatters whom they believed might be inside. But the roof was about to give way.

A mayday call crackled across fire radios as Stringer and Ankum were trapped in piles of debris. Dozens of firefighters tried to rescue them, but it was too late.

Numerous other firefighters were injured.

<a href="http://chicago.cbslocal.com/2011/12/21/criminal-charges-coming-against-owners-of-building-where-firefighters-died/&quot;.On Wednesday, Cook County State’s Attorney Anita Alvarez filed a petition for criminal charges against the owner of the building, Chuck Dai, to hold him accountable.

“On the date of the fatal fire, Mr. Dai had still failed to make the required repairs, and the building was unsecured when the fire was set,” Alvarez said.

The city’s Law Department filed a complaint about the property in Cook County Housing Court in 2007, when the building was already vacant. While the case was pending, there were seven inspections.

Among the complaints was that the roof and roof trusses were rotting, had holes and were leaking.

Dai also failed to show up for numerous court dates, and was fined more than $14,000 for not fixing the problems.

In October 2009, Dai signed a court order and agreed to pay a $1,000 dollar fine, obtain a structural engineer’s report, submit plans and apply for permits, and either make repairs or sell the building by November of this year.

Gene Murphy, the building owner’s attorney, said prosecutors cannot prove their case.

“There’s no way to prove the building was not compliant before the fire. The burden of proof falls on the county to prove this,” Murphy said.

It was believed that squatters had moved into the building and set fire to wood or garbage inside on Dec. 22, 2010. The fire went on to ignite the entire building.