Bridget Anne Kelly, New Jersey Gov. Chris Christie's former deputy chief of staff, refuses to surrender documents subpoenaed by investigators, a letter from her lawyer revealed Monday.

Christie last month fired Kelly for her role in the George Washington Bridge lane closures now plaguing the Republican, who has been labeled a likely 2016 presidential candidate. She is pleading the Fifth Amendment in response to a subpoena from the state legislative committee investigating the controversy.

Kelly's lawyer, Michael Critchley, called the committee's requests "impermissibly overboard" in a letter to the investigative committee's attorney.

“A witness is legally required to invoke the privilege against self incrimination to avail oneself of its protections,” wrote Critchley. “The 5th Amendment’s protections are not limited to verbal testimony.”

Kelly sent an August email to an official at the Port Authority of New York and New Jersey, which operates the bridge, that read, "Time for some traffic problems in Fort Lee." A month later, two Fort Lee access lanes leading to the bridge were closed.

The co-chairs of the investigative committee, Assemblyman John Wisniewski (D-Middlesex) and Sen. Loretta Weinberg (D-Bergen), acknowledged Critchley's letter in a statement to the Asbury Park Press.