In the world as far as we know, if we can not see it surely, that does not mean it does not exist, hardly are we concerned with what our eyes can not see, except a majority of it being feelings reciprocated.
Whether it may be a dog barking at something or a cat snaring, could it be that it is something they can witness?
Believing in the life after death is a consequence of being once living, perhaps there is so much, that there is no reason to speculate anything.
It would be just a guess or myself assuming of something.
If something unnatural happens know that the Jinn are amongst us in this world.
Indeed, the shaitan and his comrades are dwelling in the unseen, they are also close to a human, so there is without a doubt, things can appear but does not mean they have much power to do with it.
The most important part is that, He knows the unseen aspect of the heavens, the earth and all that is between them.
The soul of the human is either in the grave or in heaven.