an investigation into the accident was begun by the french land transport accident investigation bureau (bea-tt) and the institut de recherche criminelle de la gendarmerie nationale (ircgn) on 9 february. the scene was scanned with lasers and a 3d computer generated recreation of the accident was made to assist with the investigation. the line was to remain closed whilst the investigation continued, with no firm date set for reopening. it was reported that the weather in the preceding days had been alternating between rain and snow, with the freeze-thaw effect possibly contributing to the cause of the rockfall. the two train event recorders were retrieved from the wreckage of the train on 18 february.