PLAINFIELD, Ind. — Both local and federal investigators are one step closer to determining the cause of last week’s massive fire in Plainfield.

Wednesday marks one week since a fire broke out at the Walmart distribution center. Officials with the town of Plainfield said it took an estimated 76 hours to fully extinguish the fire thanks to the help of more than two dozen agencies working around the clock shifts.

Federal officials with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) said both local and federal ATF agents have officially completed their “on the ground” investigative work.

“The purpose of the National Response Team [NRT] is to take massive sites like these and try to put a lot of resources into it to get it to a point where the information is there for our local folks to go through,” said Suzanne Dabkowski, a public information officer for the ATF Columbus Field Division which is leading this investigation.

Dabkowski explained that although investigators have completed and collected all the evidence they need from the physical scene – their work is far from over.

The Walmart distribution center spans 1.2 million square feet and the ATF’S National Response Team (NRT) began investigating as soon as the structure was deemed safe.

“There’s just still lots of information to be reviewed,” said Dabkowski. “The type of work that’s done on the ground is actually getting into the building and seeing what’s left after the fire. Whether that points you in any place, if there’s anything that needs to be sent off to a lab to be examined – those are the general kinds of things that they’re looking for.”

Dabkowski said both of ATF’s local Indianapolis offices will work alongside the Indiana State Fire Marshal, Plainfield Fire Territory, and the Plainfield Police Department to go through and continue investigating the collective information gathered.

Officials said, up until Wednesday, crews had been busy on site sifting through debris using heavy equipment, taking note of burn patterns, and going through any interviews with Walmart employees.

“It’s just an ongoing process of talking to people and evaluating the information,” said Dabkowski.

Federal officials said while their physical presence may not be obvious going forward, they are still very much involved in the investigation.

“ATF also maintains a national fire laboratory in Maryland. So if there are samples that need to be examined, if we need to mock up situations to try to test ‘We think the fire started here, this is what that burn pattern would look like,’ — we’ve got those kinds of facilities and people can use those to try to determine exactly where the origin and cause of the fire was.”

We asked how long an investigation like this could take, but officials said even that answer is hard to predict.

“There’s just not a typical timeline that we can go with because every one of these situations is so different,” said Dabkowski. “You don’t want to rush anything, though, for fear of missing something or for fear of coming to a wrong conclusion. So you just need to to take those investigative steps and follow where they go.”

Federal officials said ATF agents are not only certified fire investigators, but a lot of them have taken additional training — even getting a Master’s degree in fire science.

“They’re experts in recognizing fire patterns,” said Dabkowski. “You name it. If there’s a specialty that could come into play in doing an arson investigation – we have those people.”