Thomas Sweatt loved fire. Loved watching buildings burn and the screaming victims run out of them. He was a mild-mannered fast-food-restaurant employee by day, but he had a dark side. Over the course of two decades, he would set enough fires in the Washington area to become arguably the most prolific serial arsonist in US history.
He started as early as 1985, torching vacant buildings and carryout joints in the District’s Anacostia. In 2001, he expand-ed his turf, incinerating homes along the border of Northeast DC and Prince George’s County. Years later, he would disclose his motives in letters to the Washington City Paper—some fires were born of powerlessness and envy over the pretty houses and nice cars he saw on his way home from work. Others were part of a sexual fantasy for Sweatt, who enjoyed watching helpless occupants struggle to escape.
In 2003, DC and Prince George’s fire officials began comparing notes on a series of nighttime fires in their jurisdictions. There were similarities: fires set between 1 and 5 am, usually at the doorway or porch of a single-family home. They concluded they were dealing with the same man.
Local fire officials brought in ATF to help with the investigation. Tom Daley, a certified fire investigator for the bureau, was part of the cross-jurisdictional manhunt.
“We tried everything,” says Daley. “DNA, fingerprints, trace evidence, interviews, psychological profiles, geographical profiles. Everything you’ve seen on CSI, every idea, every lead.”
Daley was able to track the source of each fire to the remains of a one-gallon plastic jug. The arsonist’s method was to fill a jug with gasoline, stuff a wick made out of a piece of clothing in the top, and light it.
And as any fire investigator will tell you, it’s not the gasoline itself that burns—it’s the vapors. The gasoline actually acts as a coolant, which means that in each fire a small portion of the bottom of the jug survived. Daley recovered these pieces and sent them to Ray Kuk, a forensic chemist at the newly opened Fire Research Lab. Kuk and his team were able to identify details about the device, such as the type of wick and accelerant, and they reverse-engineered their own.
Once the team figured out what Sweatt was using to start the fires, they began experimenting. Kuk built a mock wall and lit fires, filling jugs with different amounts of gasoline to establish a timeline that would reveal how long the arsonist needed to make his escape.
DNA samples were recovered from two gasoline jugs the arsonist had used, and investigators traced a shopping bag left at another scene to a local convenience store. When a pair of gas-soaked Marine Corps pants turned up near an Arlington fire, they were tested for DNA. It matched the arsonist’s.
The pants led investigators to the Naval Criminal Investigative Service, which had been looking into car fires around the Marine Barracks at Eighth and I streets in Southeast DC. NCIS had video of a car leaving one of the scenes, with a tag number they traced to a man who lived around the corner from the store that the recovered shopping bag came from. After a few days of stakeouts, ATF agents confronted Thomas Sweatt and asked for a saliva sample. He complied.
Sweatt was arrested on April 27, 2005, and charged with two deaths. As many as 45 fires were pegged to him when he pleaded guilty and was sentenced to life in prison. Since then, the number of fires he started in Washington has been estimated to be as high as 350.