A Washington state woman has been ordered held without bail in connection with the death of a U.S. Border Patrol agent in Vermont.

The killings of a Border Patrol agent in Vermont last week, a state’s witness in California, and a pair of senior citizens in Pennsylvania all appear to be linked to a fringe group of West Coast vegan activists and artificial intelligence theorists.

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.