Friday night, authorities were questioning a woman about this federal crime.
It all started when someone started a fire in a blue postal service mailbox at 1442 South Glenstone.
Two more fires were started Thursday night, one at 3951 South Campbell and one at 1707 West Battlefield.
And then, another fire was set Friday morning, again at 1442 South Glenstone.

It took a little more than a day, with these surveillance photos, for police to find a person of interest in four postal box fires.

"We treat these very seriously with a very aggressive investigation,” says Postal Inspector Don Obritsch.

In his twenty plus years as a postal inspector, Don Obritsch rarely sees this kind of crime.

"This is very isolated and unusual,” Obritsch says. “We'll go a couple years without getting any of these.”
"That's been the first one in quite a while,” says Springfield Fire Marshall Ben Basham.

One reason these fires don't happen often is they are difficult to start.
Fire officials say the limited oxygen inside this box often snuffs out flames.
But, the tight space makes fighting a fire difficult, too.

"We're supposed to use an extinguisher and if that doesn't work go to water and us as little as possible,” says Basham.

These four fires caused little damage; most of the mail was saved and will be returned to sender.
However, the punishment for setting a fire to mail in a mailbox is severe; anyone involved could face up to a year in prison for each fire.
Firefighters aren't sure what caused the fires, and so far no charges have been filed.