Ah, so now we have the murder method. He was strangled with a noose and a rather long and high up one, seeing as that poor lady said it looked like he flew up into the air. Of course, that was likely simply him being pulled up. Additional evidence lies in the direction of the strangulation mark on the neck being on a slant.
Once dead, his body was placed in a meditating position before rigor mortis and cold set in. The rope was used again, probably wrapped around his body now as opposed to just his neck, to hoist him into the air, likely using a tree branch, hence her later seeing him floating in the air.
The body later was most likely lowered to the ground, possibly into the garden directly, as if it was carried there footprints would be seen, to make it appear as a mystery corpse. I'm not sure how the rope was removed at this point, I admit.
I have no ideas as to who and why yet, but I have watched enough crimeshows with that murder method to be at least strongly positive about it being the cause.