The fires happened late Tuesday night and early Wednesday on January 28th and January 29th.
Authorities arrested two men and woman Friday. All are from Vineland.
Felix Lopez, 28, Guillermo A. Veloz, 18, and Zilia Perez, 36 are charged with arson, criminal mischief and related offenses.
"Arson is a very serious matter, even more so when directed at a government building as well as a law office," said Gloucester County Prosecutor Sean F. Dalton in a statement. "These individuals' efforts to send a message, take matters into their own hands and disrupt our system of justice have not succeeded."
The Gloucester County Prosecutor's Office was the lead law enforcement agency investigating the fires, at the request of the New Jersey Attorney General.
The January 29th fire at the Cumberland County Prosecutor's Office was first reported around 1:30 a.m. inside what was described as a sunroom attached to the brick building located on Fayette Street in Bridgeton.
The fire was contained to the one room, which sustained smoke and fire damage.
There were no injuries reported.
The blaze prompted authorities to offer a $10,000 reward after investigators determined it had been intentionally set.
Prosecutors say the fire was the second intentionally set by the three suspects that night.
They are also charged with setting fire to the law firm of Helmer, Conley & Kasselman in Vineland, N.J.
Bail for Lopez has been set at $250,000. Bail for Veloz was set at $75,000. Perez was released on her own recognizance.
The Associated Press contributed to this report.