This photo is of the window to the right of the slider in the kitchen. If you look in the upper left corner, you will see part of the cabinet above the fridge and there is something seeping from the sheet rock above the cabinet and running down the cabinet door and wall to the right. This area is directly under what has been identified on the layout diagrams as Kaylee's room. I don't know what that substance is but I have a suspicion. This leads me to think that something happened in that room.
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That photo has been discussed multiple times. The angle of the photo is being taken at a downward angle, so you are actually seeing the lower part of the refrigerator and the lower cabinets (not the ones that touch the ceiling). See the attached photo with the red circle.
In addition someone else found a photo of the same angle from a few days prior in the investigation and there is nothing on that cabinet at all. So if there is anything on that cabinet it was spilled by LE, or is some sort of chemical being used in the investigation.