Thursday, the state fire marshal's office brought in a debris reconstruction expert to sort through the rubble and literally try to piece together how the fire started.

"I feel that this is important that we find an exact cause for everybody's sake," Moundsville Assistant Fire Chief Ron Walker said.

Walker returned to the site of the Simmons Apartment building on Thursday to help investigate the fire he spent the better part of Wednesday fighting.

"I do know all of the apartments did have smoke detectors. I did hear some of the occupants say the smoke alarms were working," he said.

Walker said he does not believe there was a sprinkler system installed in the building. Some tenants jumped from third-story windows to escape the flames, but all made it out alive.

Investigators aren't just looking for answers; they're also looking back at their own notes to learn more about the structure the owners said was built in 1912.

"(We're) seeing if there were any changes made or alterations to the building itself," Walker said.

A state fire marshal has not ruled out suspicious causes.

Mark Lambert said he believes crews will finish at the scene Thursday, but that doesn't mean the investigation is over.

"There's always the possibility of laboratory analysis. We'll analyze the pictures. All the fire investigators will get together and sit down and analyze the data," Lambert said.

Officials said the fire codes vary based on the size of a building and what the building is used for.

Stay with NEWS9 and WTOV9.com for continuing coverage.

Previous Stories: April 29, 2009: Crews Believe They May Know Where Fire Started April 29, 2009: Apartment Fire Victims Jump To Safety