The attorney for one of New Jersey Gov. Chris Christie's former aides is raising questions during cross-examination in the George Washington Bridge lane-closing trial about the credibility of the prosecution's key witness.

Bridget Kelly's attorney on Friday called David Wildstein a liar. Kelly is Christie's onetime deputy chief of staff who is on trial with former Port Authority of New York and New Jersey executive Bill Baroni.

Wildstein has pleaded guilty in the case and is cooperating with federal prosecutors. He is also a former executive at the Port Authority.

Kelly's attorney, Michael Critchley, asked Wildstein whether he inaccurately said the closure was a traffic study. Wildstein called it a false statement. Critchley says it was a lie.

Kelly and Baroni face civil rights and wire fraud charges.