How do you figure? They can tell a lot from soot patterns on still standing walls, and even some from heat damage patterns on concrete foundations, but from the ash heap left after a yacht burns to the water line? I’d be surprised.
Smoke detectors in living quarters is a really good idea. However, these people didn’t die from inhaling smoke in their sleep. They died because there was no way out when they discovered their predicament, and that’s why this accident is doubly horrifying. What you need above all is some form of fire detection throughout the ship, preferably linked to a cattle siren somewhere, but in my limited experience a run-of-the-mill grocery store smoke alarm will snap me right awake even if it’s far away. IMHO, the galley is the first place you want to put one (not counting ER systems of course).