Never a dull moment around here!
I don't think that weasel is native here, there are none like it listed under native weasels. I think it might be a "Least Weasel", native to the Rockies - 8 inches long head to tail... tiny guy.
~least weasel: smallest of the three species, smallest of n.a. carnivores, 20 cm (8 in) long
~least weasel: voracious feeders, often consume half their weights in rodents each day
It would have killed the rabbit if we hadn't interrupted it, and the rabbit was an adult bunny 4X his size. Had him in a head lock. Might have already injured him too much, but the rabbit was able to run off. I always feel conflicted at those moments. They both have to eat. The weasel was not afraid of us at all.... kept coming back up to look, only mildly afraid of Gidget just ten feet away through the fence. That is why I think it was a pet maybe. Or desperate.