Seems this could be a case of mental illness in a worst case scenario.
I have a young friend who after one erratic episode with no harm to himself or anyone, he and his family decided to seek professional help. He was ultimately diagnosed as having bipolar disorder.
There are several levels of BD which afflict millions of people, and with therapy he has never had another incident.
He had an opportunity to join a large sailing vessel engaged in education and research for a long ocean voyage. Accepted, when it came time to fill out the health records paperwork, he waffled on putting down the bipolar disorder diagnosis as it may have jeopardized his position(he may not have been obligated, legally).
But he did the right thing and included the diagnosis. Thinking it through with friends and family, putting yourself on a boat for a week or more, with strangers, is a potential for a reoccurance of bipolar disorder or any other medical condition, either physical or mental, that you would be placing the boats crew into.
It's not known if the deceased was diagnosis with a mental disorder but the antidepressants sound like he may have been.
I'm not making a judgement on right or wrong (I know the boat but not the captain, well). It sounds like an impossible situation to regulate. Doomed from the start.
Forgot to add, my young friend was still accepted (rightfully) for the position on the ship and is at sea right now.