NEWARK, N.J. — The former aide to New Jersey Gov. Chris Christie who prosecutors say sent the “time for some traffic problems” email that started the George Washington Bridge lane-closing scandal is due back on the witness stand.

Federal prosecutors are expected to begin cross-examining Bridget Kelly on the morning of Oct. 24.

She was Christie’s Deputy Chief of Staff and is on trial along with a former Port Authority of New York and New Jersey executive whom prosecutors say launched the plot as revenge against a Democratic mayor who wouldn’t endorse Christie.

Prosecutors say Kelly sent the email to David Wildstein, the self-described mastermind of the plot who has pleaded guilty and is the government’s key witness.

Kelly testified Oct. 21 that the Republican Governor approved of a traffic study on the bridge. But prosecutors claim the study actually was a cover story for a political payback scheme designed to cause traffic jams.

Christie has not been charged and denies any wrongdoing.

In a statement issued Oct. 21, Christie spokesman Brian Murray said the Governor had “no knowledge prior to or during these lane re-alignment” and “no role in authorizing them.” Murray added that anything said to the contrary “is simply untrue.”

The scandal developed just after Christie won re-election handily and as his national political profile was rising. It ultimately weighed down his Presidential campaign, which ended with a fizzle in the primary season after a poor showing in New Hampshire.