BFU has published an interim report. It is accessible (in English) onr their website and the AvHerald features a decent summary.
Extract:
QUOTE
The examination of the airplane after the landing showed that the connecting lines of the left and right static ports were not linked with the respective ADMs (Fig. 5).
The maintenance work taking place prior to the flight included opening the pneumatic lines, flushing them with dry air and closing them again. The subsequent leak test and system test were meant to ensure proper function of the pitot-static system. On the respective job cards these tasks had been signed as performed and released.
UNQUOTE
While the report gives some details on the individuals involved, it is not clear which organisation achieved this; Lufthansa or Lufthansa Technik. Hopefully the final report will go beyond that and try to identify the systemic cause involved, if any, and not stop to protect the reputation of some well established organisations, including Lufthansa, Lufthansa Technik and LBA. This is common belief in Germany that they are infallible and there is no need for proper oversight.