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

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,

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.