..This guy was pretty big in regards to size and weight and in his 50s. Just a hypothesis but I wonder if he tried to fight the current and became exhausted and blew off his air trying to surface or get into the channel.
There is one thing that is bugging me. I did not look at the dive gear when the brought it on shore. I am curious to know if the weights were still attached to the BC.
Thanks for posting the additional info. I'm very sorry you had to witness the event... it can be very traumatic for everyone involved (I've been there).
In cases like this, we'll probably never really know what happened since it sounds like at some point the victim was separated from the group.
Unless I've misunderstood, the other divers surfaced, and signaled for help, but did not know where the missing diver was?
If that is the case, the victim may have been "missing" for several minutes (at least) before the group got the lifeguard's attention, and the search began. Then another 15-20 minutes past before the jetski arrived, then some additional time to recover and transport to shore... so it is possible the diver had not been breathing for
30 minutes (or longer) before CPR began. If that much time had past, then probably nothing could have been done.
It would be good to know if there were equipment issues, was there still air in the tank, weights, etc.; But with the description of the victim and circustances described, I think heart attack may ultimately be found to be to blame.
I'm very saddened to read this, and my heart goes out to everyone involved.
Best wishes.