Gunman's motive unclear, officials quiet days after shooting

VIRGINIA BEACH, Va. -- The Virginia Beach employee who shot and killed 12 people at a municipal building gave no hint of the massacre to come when he emailed his resignation letter earlier in the day, saying he was leaving for "personal reasons" but "it has been a pleasure to serve."

The gunman's two-sentence emailed resignation letter put authorities, the community and victims' families no closer to understanding why the engineer with 15 years on the job went on a rampage at work.

Investigators seem stymied. There are no indications the 40-year-old man left notes, manifestos, social media screeds or any other obvious signs of what motivated him.

The resignation email gave his two weeks' notice but no clues he was unhappy at work or held a grudge against anyone. Because the email is partially redacted, it's unclear how long before the shooting it was sent. Officials wouldn't say why they redacted it, and they declined to give an update on the investigation Monday.