I would think that the State police would have collected the can and not the WB police. According to the FB page, at the same time, the State Police were searching with lights on Cottage St. 1 1/2 miles away.
The can was found when it was getting dark, and we are getting heavy snow tomorrow, but as you say, you'd think that scene would have been processed for footprints etc. even if they already have them from the bloody crime scene in the house, just to make their case stronger.
Everything is speculation at this point.