Wouldn't the window have to be big enough for someone to get through? [spoiler=Sorry its so long ]The man was killed prior to the hanging. The suspect placed the victim in a rubber boat and covered him with a tarp. He then left the room and made his way to the balcony where he cut part of it out, taped up the holes, and used it to redirect the water from the falls. Quickly making his way back inside, he taped up a door that used to be where the hole is now located. He played the waiting game and kept the body a dry as he could. One in position under the beam, he proceeded to hang the victim followed by his escape out the window. One swing from an axe, for example, leaving a hole that would create enough stress on the door from the water to blast it and part of the wall away. Clean up the mess and the deed is done.
And I imagine the man was strangled? Probably with a rope, leaving the same markings a hanging would. Thats why there's no sign of struggle.
I suppose it could have been done without going through the window if you were to dive down and bust it out, but with all practicality, the suspect would probably have been sucked in and shot out because of how fast the water would drain.