In several instances, police say, Federici returned to fire scenes to help douse the flames.
"Hopefully, people won't have to worry about fires at 3 a.m. anymore," said West Goshen Township Police Chief Michael Carroll, who arrested Federici after spotting him leaving the Friday night fire.
Authorities are also looking into whether Federici had a role in other suspected arsons across Delaware and Chester Counties, including the Thursday fire at the Springfield Mall John Wanamakers, Carroll said. The blaze was doused by sprinklers.
Federici, who has been a firefighter for six months, is charged with setting fires almost every other day of the last two weeks in West Goshen, Westtown and East Goshen Townships, police said. The charges were filed after investigators questioned Federici at length.
It was the third time in a year that area volunteer firefighters have been accused of making work for themselves.
In June, the chief, assistant chief and two firefighters with Delaware County's Woodlyn Fire Company were charged with arson; in December, three members of the Mount Holly, N.J., Relief Volunteer Fire Company were charged.
The charges against Federici say he started fires at the following locations:
* The Windermere Apartments construction site at Route 352 and Manley Road in Westtown Township. The late-night blaze July 20 leveled the unoccupied site, causing damage estimated at more than $500,000.
* A dumpster fire two days later in the rear of the Shop 'n Bag in Westtown. It caused no injuries.
* The occupied Huntington Green Apartments in Westtown on July 23. A slow- burning fire began in the basement. Police say Federici had time to race back to his fire company before the alarm sounded - and then returned with other firefighters and helped douse the blaze.
* Two fires in West Goshen Township on Aug. 3, one in a storage shed at Goshen Terrace Apartments, the other in a clothes dryer at the Goshen Manor Apartments, less than half a mile away on West Chester Pike.
* An unfinished luxury home in the Wentworth development at Boot Road and Paoli Pike. The Aug. 7 fire destroyed the home, which would have sold for about $400,000, said Sgt. Darren Stocker of the Westtown-East Goshen Police Department.
* A barn that was being renovated in the 600 block of Reservoir Road, East Goshen Township.
* The Executive Office Center in the 900 block of West Chester Pike, West Goshen, where one person was slightly injured in a fire Aug. 10.
* A storage area at the Racquet Club Apartments in East Goshen. The small fire on Monday caused smoke damage, Stocker said.
* Three bathrooms in the Bentley Building, an office complex on Paoli Pike in East Goshen Township, on Tuesday afternoon.
Then there was Thursday's fire at Springfield Mall - and that's when police fit the pieces together, Stocker said.
He said Federici arrived at the Wanamakers fire in full uniform, which is ''a little out of the ordinary," Stocker said, given that his West Goshen department is many miles from the mall.
More unusual, Stocker said, was that Federici arrived ahead of local firefighters. Springfield fire officials then contacted West Goshen Township.
Delaware County officials said the Springfield fire, which sent one Wanamakers employee to the hospital with smoke inhalation, was still under investigation.
The last fire was the most dangerous.
About 9 p.m. Friday, Stocker said, Federici broke into the basement of the ''B" building of the Huntington Green Apartments and lit a pile of debris.
"He went back for more," said Stocker, noting that an earlier fire had been at the Huntington.
Police Chief Carroll of West Goshen - who police said was tailing Federici by then - said he noticed Federici's car as the firefighter slipped out of the apartment complex - before the fire inside the "B" building was noticed by anyone.
A half hour later, when flames were spreading through the basement and five firefighters had already suffered smoke inhalation and cuts, an eager Federici
reappeared at the scene, Carroll said.
He was suited up and ready to help when Carroll and others arrested him.