When the "D.C. Sniper" John Allen Muhammad and his then-teenage accomplice Lee Boyd Malvo went on a three-week shooting spree back in 2002, their bloody rampage did more than leave a trail of victims and spread panic throughout the capital region. The Beltway sniper attacks also hurt math and reading scores at elementary and middle schools in Virginia that were in close proximity to the shootings, according to a new study published by the National Bureau of Economic Research.