The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives sent an alert to federally licensed firearms dealers a day after the shooting seeking information related to any gun purchases by Michelle Jacqueline Zajko.

The weapon that killed Agent David Maland last week in northern Vermont was bought by a person of interest in a double murder two years ago in Delaware County, state police say.

A woman charged in the fatal shooting of a U.S. Border Patrol agent in Vermont is scheduled to appear in federal court.