I doubt the AAIB digs all that deep, in GA accidents. Most GA planes have a long history with lots of gaps in the records.
10540
I dont know so only guessing but I would imagine where there has been loss of life there would be a thorough investigation which would also be required by the police to discount suicide, murder etc.
We also have to remember that it is not only the deceased persons family who would be looking to make a claim but also a claim would be made to damages on the ground where the aircraft came down.
Pace