WASHINGTON (AP) - The Justice Department is dropping its investigation into whether David Petraeus' mistress, Paula Broadwell, stalked a romantic rival online.

Broadwell's lawyer, Robert Muse, gave The Associated Press a letter from U.S. Attorney Robert O'Neill that says no federal charges will be brought in Florida related to "alleged acts of cyberstalking."

A retired general, Petraeus resigned as CIA director in November after acknowledging the extramarital affair, which was exposed after Broadwell emailed Tampa socialite Jill Kelley, allegedly warning Kelley to stay away from Petraeus and Gen. John Allen, the U.S. commander in Afghanistan.

Kelley reported the emails to the FBI, triggering an investigation that led the FBI to Kelley's emails to the married Allen, who is now under investigation by the Pentagon's inspector general.

A Justice Department spokesman declined to comment.

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