NEWARK, N.J. — The former aide to New Jersey Gov. Chris Christie who prosecutors say sent the “time for some traffic problems” e-mail that started a scandal was due back on the witness stand.

Prosecutors were expected to begin cross-examining Bridget Kelly this morning. 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 e-mail to David Wildstein, the self-described mastermind of the plot who has pleaded guilty and is the government’s key witness.

Kelly testified Friday that the Republican governor approved of a traffic study on the bridge. But prosecutors claim the study actually was a cover story for a scheme designed to cause traffic jams. Christie has not been charged.

By The Associated Press