If there was no sign of a struggle, how could he have been beaten to death? Also, isn't it possible he fell once, fracturing the back of his head and then fell again getting to the bed and broke his face?
Falls are weird. A friend of mine, her mother fell in her kitchen a week ago and struck her head. The damage was severe. They attempted brain surgery, but it was not successful. She never regained consciousness and died last night.
My sister in law fell the same day in her laundry room. She suffered a brain bleed and broken shoulder and went blind in her right eye. They couldn't stop the bleed for days and she eventually went blind in her left eye. She was always conscious. The brain bleed did finally stop and vision is returning in her left eye. But she has a long road ahead of her.
These were small, slim women. A big, heavy guy falling in the shower and landing directly on his head could be catastrophic. Hell, maybe they did off him, but why would they do it in a fashion that raises questions?