Call the police and let them handle this inconsiderate person.
I'm truly sorry about the loss of your friend. I lost my best friend to cancer last November so I know it's rough.
I'm also one of those people that carry armloads out of estate sales. Although it hurts to see her things go (it's like losing them all over again and it makes their passing so final) please know that the people buying them really want them so they're going to be taken care of. I bought my high school English teacher's Featherweight and I can tell you, it's cherished probably more than when she had it. I also bought some vintage hankies from one of my mom and dad's neighbors and they too will be cherished in a butterfly quilt.