Younkers fire: Federal experts start probe on west of site

Federal investigators on Tuesday spent their first day inside the fire-ravaged former Younkers building in downtown Des Moines as they began trying to determine how the blaze started.

Investigators with the Bureau of Alcohol, Tobacco, Firearms and Explosives were in the building's west side, including the area that housed the former department store's well-known Tea Room, bureau spokesman John Ham said. That section of the building was not as badly damaged by the fire as the east portion, where flames consumed entire floors.

Investigators will be clad in white suits designed to protect them from chemicals and other toxins, including asbestos, as they sift through the fire's rubble, Ham said. They will also wear masks to filter the air they breathe.

The Younkers blaze was first reported at 12:52 a.m. Saturday. Firefighters doused the ruins well into Sunday, as onlookers gawked at what was left of the smoldering structure of steel, concrete and brick. The 115-year-old building, which was being renovated into apartments and retail space, was set to be a cornerstone for a revitalized Walnut Street.

Members of the federal ATF team, including arson investigators, engineers and a chemist, arrived in Des Moines on Sunday and Monday and have since conducted hundreds of interviews with firefighters and people who were around the building early Saturday morning as it burned, Ham said. Fire engineers are reviewing video of the fire to see how it burned and its "behavior," he said.

"That's been a tremendous help to our fire engineers and our cause-of-origin specialists," he said.

Investigators looked for spots that might have burned hotter than others or "indicators" of how the fire burned, Ham said. Being inside the building also helps investigators get an idea of how construction was unfolding in the building, he said.

It's unlikely that ATF investigators will enter the eastern portion of the building while they are on the site, Ham said. It's also unclear whether the investigators will do any excavation on the site, simply because of the hazards posed by shifting debris, he said.

"We're not going to do that here because it's not safe," he said.

However, inability to dig out the site won't hamper the investigation, Ham said. Investigators have still not ruled out any potential causes.

One key tool being used by investigators and engineers is 3-D forensic mapping that re-creates the inside of the Younkers building with exact measurements, Ham said. The mapping can then be paired with a fire modeling program to develop theories of what caused the fire and where it started, he said.

Investigators continue to watch for debris falling off nearby buildings such as the Hub Tower and EMC Insurance building, though winds have died down since Monday, Ham said.

Both buildings were damaged by the fire.

Des Moines Fire Chief John TeKippe on Tuesday warned people to avoid the area near the former Younkers building.

"There's still a lot of glass hazard from being too close, especially in the winds today," he said. "The adjacent properties are doing all they can to mitigate glass. But probably the best place to look at the building is on the Internet."

— Register staff writer Lee Rood contributed to this story.