The woman accused of shooting and killing a U.S. Border Patrol agent will remain behind bars.Teresa Youngblut allegedly shot and killed David “Chris” Maland during a traffic stop on Jan. 20 on Interstate 91 in the town of Coventry not far from the Canadian border.

A Washington state woman charged in connection with the fatal shooting of a U.S. border patrol agent in Vermont had been in frequent contact with someone whom authorities have linked to homicides in Pennsylvania and California,

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