Half of that is rubbish. To date I've heard 4 versions of who discovered him in the boat. The media cannot bring themselves to just say we don't know yet so say anything to keep the story going.
The owner saw blood, lifted the tarp and saw him (unlikely) The houseowner saw the shed door open and some bloody clothes. The ownner noticed one of the straps holding the tarp down was loose. And the latest one is a passerby saw blood on the boat and called Police. I'm thinking the last one although we could have another 50 versions soon.
