Methylene blue manufactured for fish tanks was used to add to a solution for an IV drip. Anything injected this way is required to be manufactured for human medical use and would be sterile. This product is neither.
Firefighter Tommy points to a carbon monoxide detector mounted on the ceiling, which a firefighter would know is in the wrong place. Carbon monoxide detectors are placed close to floor level as carbon monoxide is heavier than breathable air and displaces it as it fills a space. The alarm on the ceiling would have activated only after the carbon monoxide completely filled the room and long rendered anyone inside the space unconscious.