NEWARK, N.J. (AP) — Federal prosecutors are cross-examining a former aide to Republican New Jersey Gov. Chris Christie who is on trial in the George Washington Bridge lane-closing scandal.

Bridget Kelly was back on the witness stand Tuesday for her third day of testimony.

Kelly testified Monday that she told Christie a Democratic mayor had expressed concern the resulting traffic jams in his city were political retribution. She said Christie lied three months later when he told reporters no one on his senior staff knew of the plot.

Kelly was Christie's deputy chief of staff. She's on trial with a former Port Authority of New York and New Jersey executive who prosecutors say launched the plot as revenge against the mayor because he wouldn't endorse Christie.

Christie hasn't been charged.