RedactedNarrative: Vessel Operator reported that he was fishing with his father on the St. Joseph River.  He reported that he and his father/victim fell overboard when the father stood up in the boat to urinate over the side and lost his balance tipping the boat over.  Son was not able to hold onto his father in the river; he had to let go.  He floated down river and came to rest against a tree that had fallen from the shore into the water and was partially under the water. He stated his body came to rest against the tree and he pulled himself onto the shore via the tree and then climbed up through the woods.  He stated he eventually made his way to N River Road where he was able to flag down a vehicle and call 911.  Neither were wearing a life jacket.  Son stated that his father was in poor health and that he was on several medications for his heart and prescription pain medications.  The outcome of the autopsy: Dr. believed that the stress of the event of being in the water and trying to stay above water caused substantial stress to the victim's body and heart which made him go under water and subsequently drown.  There were no suspicious injuries or markings on the victim ruling out foul play.