A report in the UK’s investigation of road traffic accidents has been published recently https://www.racfoundation.org/wp-content/uploads/International_review_of-road_collision_investigation_approaches_Jeavons_Runacres_December_2020.pdf .
It is an excellent review of the approaches taken by countries worldwide. This highly-readable report was written by Saul Jeavons and Adrian Runacres of Transafe Network ltd and highlights the considerable differences and investment into deaths per 100,000 inhabitants. It highlights where the UK falls behind other countries, particularly northern European ones. It argues strongly for there to be an independent Investigation branch, possibly with links to investigation branches dealing with other modes of transport.
It is pleasing to have contributed to the initial stages of this review.