<modsnip - off topic>
I don't think there is a basement. The word was introduced by one of the family members, early on.
I think the person who entered is confused and thinks it's "the basement." Perhaps that's the term they use for first story of a two story house. They would not be alone in that. I was recently part of a discussion (I think it was here on WS) about what "attic" really means. I think it is the Idaho Four thread. I was amazed at how differently both words are used around the English-speaking world. I have to say that I would have considered the first floor of 1122 King Road to be a basement - but maybe it isn't? I don't know the technical definition and I don't know how people around the nation use the word. Basements are not a thing in most of the places I've lived.
There's a picture of a screen removed from a window - so I took that to be the "basement" of the house, because the woman said it was a basement and that she removed a screen. However, I do believe she is mistaken about there being a basement and she entered on the first floor, "went to another part of the house" (the rest of the house) and opened the back door, finding the horrifying sight of a dead body - and someone known to her. This was early on, that she said this, and like anyone, in the aftermath of such a close personal tragedy, the mind races and glitches.
If there is a basement, I can see no evidence of it. You can see the screen on the ground at about 0:18 of this video from the New York Post:
It's the first real time picture of the house, from the front, that I know about.
IMO