Here's the reality ... anybody who knows anything about this accident has already been told by lawyers and by the agency they represent not to say anything about it in public. Doing so can only harm them. As this and most other threads in this forum demonstrate, in the absense of information, people speculate. Speculation ultimately leads to a mentality where people outdo each other with "plausible" theories about what happened, and who is to blame. The "experts" trot out their pet theories about how the agencies and instructors are all incompetent, and if only we'd teach scuba like they did back in the '50's, this wouldn't have happened. At that point, anyone with any real information would be foolish in the extreme to say a word ... they'd be lynched by a crowd now "angry" that this happened and eager to blame someone.
Even if the people with the real information were not dealing with the constraints of a legal system that's always looking for someone to blame, they'd be foolish in the extreme to say a word in here ... they'd be torn to shreds.
Meanwhile, the families of the victims inevitably find these threads, read the words of the blame-seekers, and hurt even more because they don't know enough about scuba to understand the difference between what's plausible and what's just someone seeking to show the world how "knowledgeable" they are.
Everyone comes to these threads claiming to want to learn from the mistakes of others. Sadly, there's nothing to learn ... there's only the potential to cause further harm to people who are already hurting in ways that most of us can't even imagine.
The reality is that the only two people who could have truly told you what happened are dead ...
... Bob (Grateful Diver)