The federal case was investigated by the Internal Revenue Service Criminal Investigations. Lawton faces a maximum sentence of 20 years in prison and a $500,000 fine.
Lawton was arrested Sept. 21 in Elkton, Md. as she got off a bus still carrying the bust - a 25-pound, 28-inch-high piece of art made in 1778 by Jean-Antoine Houdon while Franklin was visiting Paris.
But the saga of Ben's bust began the previous month, Lawton told police, after she was fired from the owner of the Bryn Mawr home.
Lawton said she wanted revenge and so took the one thing that she was warned never to touch - the plaster bust.
Police released those details it a preliminary hearing in Lower Merion several days after her arrest. At that hearing, police released an interview in which Lawton said she had an accomplice in the theft - a man who broke into the house while she waited in a car.
Lawton reportedly said the accomplice broke into the home of lawyer George A. D'Angelo by kicking out an air conditioner. The accomplice, a male, grabbed the bust in the drawing room.
But the plan was foiled when a car pulled into the driver as the thief went back into the house to steal its pedestal. Lawton and the accomplice fled, but not before the car's occupants recognized her.
Lawton said she left the bust overnight in a Dumpster outside an apartment building near 31st and Parrish Streets. Facing arrest, she fled to a relative's home in Mobile, Ala.
Frightened, she then hopped on a Grehound bus. She was arrested as she got off.
The bust was recovered, but it was cracked.
Lawson was returned to prison in Philadelphia on $1 million bail.
However, authorities are still searching for a another item stolen during the burglary - a shadowbox with a picture of operetta composer Victor Herbert and his baton.
Lawton told police she never knew the accomplice stole the $80,000 object until gold by police.