RedactedNarrative: On 09/17/2016 at approximately 1052 hours, I left the Wahweap Marina on boat patrol to investigate a report of a boat accident at the entrance to Navajo Canyon.  This accident was originally reported to and responded to by Park Service Rangers.
  I met with Ranger#1 north of Navajo Canyon as the call was completed prior to my arrival. Ranger#1 gave me the information that the patient had been flown to Flagstaff Medical Center.  Ranger#1 stated that to his knowledge there was no damage to the boat and that the operator of the boat had been flown for precautions to Flagstaff.  Ranger#1 stated that he had noted only a small laceration on the victim`s forehead.  He also stated that the victim may have suffered a period of unconsciousness.
  I noted that the vessel involved in the incident was being towed back to Wahweap Marina by Executive Services.  Ranger#1 informed me that the boat had been taking on water.
  I returned to the Wahweap docks and proceeded to Marine Services at Wahweap.  This was at approximately 1336 hours.  I spoke with Personnel#1 at Marine Services and was able to view the boat out of the water.  I noted that the boat was draining a significant amount of water from the transom drain.  Personnel#1 informed me that the water level in the vessel had been up to the side of the engine block.  Personnel#1 was unsure of how the water had been getting into the boat.
  I noted rub and wear marks on the hull but was unable to determine their age. I also noted what appeared to be a new scratch/divot on the keel of the boat, towards the bow.  I noted water dripping from the divot.  Apparently, the divot was deep enough that water had entered the hull.  I took pictures of the damage to the boat.  I also noted the boat`s bow numbers and make and model.  At this time, Personnel#1 received a call from family who knew the owner of the boat.  He identified the owner of the boat as Owner#1 and passed information on to me that there had been others aboard Owner#1`s boat.  Personnel#1 was also able to provide me with Owner#1`s address in Greenehaven.  He stated that Owner#1`s wife would be at that address.
  At approximately 1411 hours, I arrived at 1915 Wahweap and met with Owner#1`s wife.  Owner#1`s wife immediately informed me that Owner#1 had been diagnosed with carbon monoxide poisoning.
  Owner#1`s wife stated that that morning Owner#1 and two of his friends, one of whom included Passenger#1, had left Wahweap to go fishing.  She stated that to her knowledge the boat was taking on water.  Owner#1`s wife stated she had received a call from the flight crew that had flown Owner#1 and had been given the information that he had carbon monoxide poisoning and that the doctor at Flagstaff Hospital wanted to keep Owner#1 overnight due to his past medical conditions. 
  At approximately 1421 hours, I went next door to 225 North Wahweap in Green Haven and spoke with Passenger#1 and Passenger#2 who had been on the boat with Owner#1.
  Passenger#2 provided the bulk of the information stating that upon arrival at Navajo Canyon to go fishing, they had noted that the boat was taking on water in the cabin portion of the boat.  They did not know how this was happening.  He stated that both Passenger#2 and Passenger#1 noticed that Owner#1 was beginning to shake and lean to one side.  However, Owner#1 denied that anything was wrong.
  Passenger#2 stated that within approximately a minute the following had occurred, Owner#1 possibly lost consciousness, but definitely fell to the deck of the boat.  The boat proceeded to impact the wall of the canyon and neither Passenger#2 nor Passenger#1 were sure of the exact chain of events, as to whether Owner#1 passed out and then fell, losing control of the vessel or if the vessel struck the wall followed by Owner#1 losing consciousness.
  Passenger#2 stated that Passenger#1 put out a distress call and they were assisted by the Navajo Canyon Tour Group Boat followed by Park Rangers.  Owner#1 was tran...
  