Her poor 4 year old was found sleeping on the boat.
Yeah, it could be a life changer... Turns out Mary Kay Latourneau (sp?), at 11 years old, was in a pool where her 3-year old brother drowned. Many people through the years thought that she had stunted maturity. At 4, well that's not likely but there may be some underlying guilt later on.
I'm reminded of a UK singer who was with family swimming when a speeding boat hit her. A straight drowning isn't typical, so injuries/medical conditions must be involved or it was suicide.