Surely a lot of caution is needed when using Twitter as a primary source? It can be reliable but one of the most interesting aspects of this case is the amount of rumour vs confirmed facts.
TBH I'm a bit dubious about the whole 'bone saw' business as there's no reason to use a bone saw unless you're doing amputations, want 'operation quality' cuts, etc, all of which are totally unnecessary if you're just slicing up a body in which case a large hacksaw will do the job just as easily, possibly more quickly, certainly raise less questions at customs, and could be binned easily afterwards. Taking a saw home afterwards in your hand baggage is just one of those many things about this which make no sense at all, unless someone deliberately wanted sensational headlines.
Edit: if, as @Crash has suggested, it was found on their way out and the Turks already knew about the incident, it makes even less sense and puts the direct lie to the idea that the Turks want transparency and to know what happened, etc, since nine of the fifteen had diplomatic status / immunity.