(CNN) -- Federal prosecutors in New Jersey have subpoenaed documents from political groups linked to Gov. Chris Christie over an unfolding scandal involving suggestions senior state government appointees abused their authority to punish a local mayor politically, according to a law firm involved in the case.
The office of U.S. Attorney Paul Fishman has sought documents from Christie's reelection campaign and the New Jersey State Committee, which is controlled by the governor, relating to the alleged scheme that has rocked Christie's administration, Mark Sheridan of Patton Boggs said in a statement.
The firm is representing both groups in investigations by the Justice Department and a special state committee, which has also sought materials from them, he said.
"The campaign and the state party intend to cooperate with the U.S. Attorney's office and the state legislative committee and will respond to the subpoenas accordingly," Sheridan said.
Rebekah Carmichael, a spokeswoman for Fishman, said that "we can neither confirm nor deny any specific investigative actions."
Sheridan said the subpoenas involve investigations of whether top Christie appointees orchestrated traffic gridlock around the George Washington Bridge in Fort Lee over several days last September in an apparent bid to punish that town's mayor, Mark Sokolich, for not endorsing their boss for reelection.
Christie denies any knowledge of the alleged scheme, but he fired one aide at the center of it and three others whose names have surfaced in e-mails around the scandal have also left their jobs.
The scandal has heated up with Christie taking the oath of office for a second term this week. It has also raised questions about his brash governing style that has propelled him to the top of polls of potential Republican presidential candidates in 2016.
The U.S. Attorney's office and state legislative investigators are also looking at allegations top New Jersey government officials pressured another local mayor, Dawn Zimmer of Hoboken, to back a redevelopment project favored by Christie as a condition of receiving Superstorm Sandy relief funds for her city.
The officials, including Lt. Gov. Kim Guadagno, denied the accusation.
Representatives from Fishman's office and the FBI interviewed two of Zimmer's staffers this week, according to a source close to the investigation.
Chief of Staff Dan Bryan and communications manager Juan Melli told federal investigators Zimmer had told them Guadagno linked Sandy relief to her support for the development project.
Zimmer has met with Fishman's office as well.
CNN's Chris Frates contributed to this story.