The New Jersey legislative committee investigating the mysterious closing of access lanes to the George Washington Bridge last September has subpoenaed a cellphone carrier in an effort to uncover text messages exchanged by Gov. Chris Christie and a top aide as the governor’s administration sought to contain the fallout from the ensuing scandal.

The aide, Regina Egea, told the panel last month that she texted the governor in December after a legislative hearing at which employees of the Port Authority of New York and New Jersey, which controls the bridge, first rebutted the administration’s assertion that the lanes had been closed as part of a traffic study.

The authority workers also said during the hearing that Mr. Christie’s staff at the agency had instructed them not to give notice of the lane closings to the police or public officials in Fort Lee, N.J., the town shut down for four days by the resulting traffic snarl. The town’s mayor maintains that the closings were political retribution for his refusal to endorse the governor for re-election.

In the subpoena released on Wednesday, the committee asks AT&T to produce records of all calls and texts to and from the cellphone of Ms. Egea, the governor’s liaison to the authority, during December.