The average cruise ship stateroom is scarcely bigger than a phone booth, metaphorically speaking. The bed dominates the room, and you have to pick your way around it.
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That's true...I've been in some of those staterooms. However, most ships also have suites which are somewhat larger than the average stateroom. I don't know if the couple had an ordinary stateroom or a suite.
I will say this about hearing anything -- soundproofing, even in the suites, leaves a lot to be desired. Even years ago when I was a more sound sleeper than I am now, I would wake up on these ships at the slightest noise. So if she was sleeping (and no one it seems knows for sure that she was), she would have had to have been drugged, drunk or otherwise unconscious to not hear anything.
It's really a small room, certainly not a suite.
It's like the Holloway case......not much known for the amateur sleuths like us, LOL.
Leni