New details regarding the fatal shooting of Minnesota-born U.S. Border Patrol agent David Maland have been revealed in court. The 44-year-old was fatally shot while conducting a traffic stop in Vermont on Jan. 20. He was from the Blue Earth area and graduated from Fairmont High School.

MANCHESTER, New Hampshire ( WMUR) -- Investigators said the guns allegedly used in the killing of a Border Patrol agent in Vermont were purchased in that state. Teresa Youngblut is facing two felony charges in connection with agent David Maland's death.

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.

As the sprawling investigation unfolds, here’s an overview of the key figures involved and their alleged connections.

Associates of woman in Border Patrol agent's shooting death tied to other homicides in Pennsylvania and California.

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

The gun used in the shooting death of a Delaware County couple was used in connection with the line-of-duty shooting death of a border patrol agent in Vermont, officials said.

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.