Lots of people blaming the trooper, but it seems to me that there was some confusion as to where the accident was.  My speculation is that the good Samaritan called it in to APD, who thought it was on the troopers side of the Knik river and dispatched a trooper.  The trooper, probably believing that the witness and APD had gotten the story straight probably carefully searched on the north wide of the river, and was unable to find any sign of a car leaving the road.  The next day when the witness called back, the APD dispatcher once again tried to turf it to the troopers, but apparently the description of the location had been refined, and the troopers were able to tell APD that that location was on the South side of the Knik river in APD jurisdiction.  It seems like the error, if their was one, was made by either APD dispatch, or by the witness originally giving an unclear location.