Thought it was "The Dead are Alive" - WRONG!

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Around '72 - '73 I was forced to watch a horror flick with my family at the Norwalk Twin Cinema in Norwalk, CA. I begged my dad to watch a western in the adjacent theatre but to no avail. I was scared to death as a kid, and knew this wouldn't end well. My recollection is that the movie was a cemetery setting, large mansion on the property, and vertical stones all about. Every once in awhile the scene would return to a particular stone and show a hand slowly making its way through the soil. When it would return, the hand would be further and further out until finally the entire being was above ground, and floating toward the mansion. Inside there was a man wearing what looked like a smoking jacket/robe, writing at a desk with what may have been a quill pen in a Victorian looking room. A decomposed, greenish hand slowly placed its hand on his shoulder, and he slowly turned his head back to see who it was when the camera flashed to the face of the hideous corpse. I couldn't enter my room alone at night for a couple years after that if the drapes were open!

I thought it was "the Dead are Alive", but managed to see it on Amazon a couple years back and it definitely wasn't it. Perhaps this scene resembles many horror movie scenes, but hopefully someone will know. Thanks in advance.