You don't need to take a rescue diver class to know how to cut off someone's air supply. Heck, you learn where all that connects in the first pool session of open water.
That's my point though. He's a fool and frankly so are the people who took five years to figure this out - that's equally stunning to me. MINIMAL amounts of training would have saved her life, and he was all the way up to rescue diver, which you can't take till you've taken a class in open water, advanced open water, and emergency first response.
Sorry, I wasn't clear, I think he took the class to make himself look innocent after that fact, like how could he not be able to save her with his training. Like when you said it would take minimal amounts of training it I believe in his mind he thought it would not make him look guilty of premeditation but of stupidity or panic.
Just this past dive trip I took, one of the two guys I was diving with, Andy, had some kind of blockage in the second stage of his reg and wasn't getting air. I swam right over with my octopus (it's a second mouthpeice attached to your regulator for exactly these situations) and let him breath off of my air till we figured out what was wrong (even though he could have used his own octopus, but he was a little panicked at that point and not thinking clearly). It was no big deal and once it was fixed we continued the rest of the dive. Her having a legit air problem should have been exactly that kind of blip on the radar with the worst case scenario being the two of them having to surface earlier than they would have otherwise. I've never heard of someone dying from a lack of air unless a) they were diving alone, b) they were diving so deep that nitrogen narcosis became a factor or c) they got tangled in something. Hell, the fact that she didn't swim to the surface in a panic and risk dying of the bends tells me all I need to know. Someone drowning doesn't sit at the bottom of the ocean gulping water.
There were many articles about this and everything that you've stated here has been pondered as well. I was hoping you'd see this thread because of your diving experience it would be great to see your reaction.
The more I think about it the more I can't believe it took them five years.