After searching your site and looking at the matching photos, the attached beetle does look similar to plinthocoelium suaveeolens. This one was discovered just outside Montpelier, Vermont trying to fjord our local river. It was at least 1.5 to 2 cm long.
Your Ground Beetle is not Plinthocoelium suaveeolens. We are checking with Eric Eaton to see if he can give us a species name. Eric quickly responded with this information: ” Carabus auratus, a European import. Had no idea they were here until this image prompted a Google search. Wow. Eric “