--SPOILER--
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The mother is first threatened with a knife by her youngest daughter, and finally stabbed (one time, not shown directly but heard and you see the reaction) to death by the other.
At about 1 h 11 minutes. Spoiler alert but it is best to look away once Doris whispers in the boys’ ear and his eyes show he is possessed, too. It happens pretty fast after that and also very suddenly. It takes about a minute, you hear the people leaving the room and going downstairs. At 1 h 17 min 55 seconds or so the body is seen again later during the chase a few times, at about 1 h 18 mins and 10 seconds or so and dangling at 1 h 19 mins 10 seconds. I would recommend skipping a couple of full minutes. The body finally falls to the ground at about 1 h 20 mins. After that there is no hanging.
Someone is hung by the neck and it may have been self-inflicted (it’s ambiguous how exactly the character got into the noose). However, it is strongly implied that the character was possessed and/or influenced by an evil spirit at the time, so they were not acting of their own accord.