Fire Research Laboratory Senior Electrical Engineer Michael Keller, left, and Special Agent Fire Investigator Lenwood Reeves, right, walk through one of the center's medium-sized burn cells, which studies fire behavior, on Friday in Beltsville. (Andrew Harnik/For The Washington Post)

The La-Z-Boy recliner didn’t have a chance. Neither did the golf cart, the three Corvettes or the replica of a Comfort Inn hotel room.

They all went up in flames at the world’s largest fire research lab, leaving nothing but smoke, ash, charred metal and data. Lots of data.

“If it will burn, we’ll set it on fire,” said Lenwood S. Reeves, a certified investigator at the Fire Research Laboratory in Beltsville, Md., where he and nearly 70 colleagues with the Bureau of Alcohol, Tobacco, Firearms and Explosives work to understand how fires start and why.

This is the only facility in the world dedicated to examining criminal fires, ATF officials said. Carpenters, engineers and chemists help investigators answer important questions after a fire has been doused and the smoke clears: How and where did the blaze start? And, in some cases, who did it?

It’s “CSI” meets “Backdraft,” but with real science. (And no Baldwin brothers.)

Fire Research Laboratory Senior Electrical Engineer Michael Keller, right, and Special Agent Fire Investigator Lenwood Reeves stand in one of their classrooms at the Bureau of Alcohol, Tobacco, Firearms and Explosives Fire Research Laboratory on Friday in Beltsville. (Andrew Harnik/For The Washington Post)

In April, investigators at the lab will set three dried-out Christmas trees ablaze as they seek to better understand the fire that killed a couple and four of their grandchildren in an Annapolis mansion last month. Investigators placed the trees in their stands at the lab Thursday. They will water and light the trees the same way homeowners Don and Sandra Pyle did in the weeks leading up to the Jan. 19 fire, one of the deadliest in Maryland in years.

A faulty electrical outlet used for the tree lights probably ignited a tree skirt, setting off an inferno, fire officials said. Authorities believe a 15-foot Fraser fir displayed in the great room of the Pyle home fueled the fire, allowing it to quickly consume the 16,000-square-foot mansion.

“It’s a very unique situation, because typically we wouldn’t do this for a case that was ruled accidental or not involved in any kind of federal prosecution,” said Dave Cheplak, a special agent and spokesman for the ATF. “But the fire research lab is here to support state and local investigations.”

The ATF’s sprawling facility was built in 2003 after a national conference of investigators agreed that authorities needed to adopt a more scientific approach to understanding fires. In 2013 alone, the ATF conducted more than 1,700 fire and arson investigations.

The work can be simple, such as putting a toaster’s singed wiring under a powerful microscope or examining ashes from a scene to determine what fueled a fire.

When a fire is more complex and mysterious, investigators will turn to controlled burns in the research lab. In the cavernous burn rooms, where exhaust systems whirr and electric saws buzz, investigators reconstruct entire buildings — down to furniture, paint colors and crown molding — to learn how a fire moved and how quickly it spread.

The lab is one of only two or three places in the world able to hold structures up to three stories high and state-of-the-art hoods and exhaust systems big and powerful enough to collect data from controlled burns.

Fire Research Laboratory Senior Electrical Engineer Michael Keller shows examples of macro photography work on Friday in Beltsville, Md. (Andrew Harnik/For The Washington Post)

It’s all about asking questions, coming up with hypotheses and testing everything out, Reeves said.

“You have to look at everything, all the circumstances together, and come to a conclusion,” he said. “What they do up here with the testing is answer certain pieces of the puzzle to help us fill in the answers to get the overall picture.”

Evidence collected at the lab has been crucial in solving some big cases.

A decade ago, investigators successfully nabbed a serial arsonist who had stalked the Washington area for more than two years. Starting in at least early 2002, fires mysteriously erupted at nearly 50 houses in the region. Two elderly women were killed.

Authorities linked Thomas A. Sweatt to the fires through DNA and pieces of clothing found at the scenes. At the research lab, ATF investigators replicated the firebombs Sweatt made from plastic jugs filled with gasoline that he would leave on porches. During the tests, they learned that the bombs didn’t explode right away, giving Sweatt time for a getaway and explaining why he was able to elude authorities for so long.

“All of us were on edge, not knowing when this person would strike next,” Anthony A. Williams, the District’s mayor at the time, said after Sweatt’s arrest.

Sweatt is serving a life sentence in federal prison after pleading guilty to setting dozens of fires.

In some cases, ATF investigations keep people from being wrongfully convicted, said Michael Keller, a senior electrical engineer at the research lab. Keller said he has investigated three potential death-penalty cases in which the fires were eventually ruled accidental.

In 2009, an Iowa man could have faced a death-penalty trial after placing a 5-month-old boy in a car seat on a glass stovetop. The infant, the son of the man’s ex-wife, burned to death. Some investigators wanted to charge the man with murder, Keller said; they presumed the couple’s stormy relationship was the motive. But the man said he placed the baby on the stove because it was the only flat surface out of the reach of a dog in the house.

After several tests, investigators deemed the infant’s death an accident. They re-created the rocking motion of the car seat and found it could bump a knob on the stove and light a rear burner. The re-creation also determined that within five minutes, the seat and the child went up in flames.

“Every time we walk into court, every time they walk on a scene, people’s lives and livelihood [are] at risk as a result of our investigation,” Keller said. “We don’t have a dog in the hunt other than to make sure we get the right answer.”