(CNN) - Court papers show the FBI has contacted Chris Christie's former campaign manager as part of a federal probe of a traffic scandal that has upended the New Jersey governor's administration.
Bill Stepien, in arguing why he cannot comply with a subpoena issued by a state legislative committee also investigating the scandal, said federal agents have visited his home and questioned people who know him, according to court papers.
"In recent weeks, federal criminal investigators have made their interest in him plain, traveling to his home and importuning his landlord and presumably others to provide information about his conduct and character," Stepien's lawyer, Kevin Marino, said.
Specifically, the court documents claimed that an agent called Stepien on his cell phone in January, and most recently questioned his landlord.
The FBI asked "if he was married, was a rowdy tenant, did he pay his rent on time," according to the papers.
It's the first indication that federal investigators have actually been on the ground as part of its probe of the Christie administration.
Stepien managed both Christie gubernatorial campaigns, but Christie asked him to leave his political organization in January after his name surfaced in emails around the scandal involving abrupt traffic lane closures near the George Washington Bridge in Fort Lee last September.
Both federal and legislative investigators are probing suggestions that top Christie appointees orchestrated the lane closures as part of a political scheme to punish the mayor of Fort Lee for not endorsing Christie for reelection.
Stepien has not been accused of any wrongdoing and Christie denies knowing about the traffic gridlock over a work week until after it happened.
Christie, a Republican viewed as a possible presidential candidate in 2016, also has said repeatedly he knew nothing about any related political mischief by people working on behalf of the state.
Stepien cannot answer the state legislative subpoena because doing so would violate his right against self-incrimination, Marino argued in the court filing.
“Mr. Stepien is undeniably a subject, if not a target, of both, meaning the committee investigation and U.S. attorney probe, Marino said.
The U.S. Attorney's office in Newark had no comment on the Stepien matter.
An attorney for Bridget Anne Kelley, a top Christie appointee fired over the scandal and fighting a legislative subpoena, said he plans to file court papers on Thursday.