The following solution is supposed to clarify the incident having occurred in the Bundesliga match between Bayer Leverkusen and Borussia M'gladbach, refereed by Felix Brych, that was put up for debate in this blog post.
The official assessment issued by DFB's referee committee member Lutz Michael Fröhlich upon The Third Team's request:
No deliberate handball and therefore no penalty, because the player who handled the ball (Arango, white 18), raised his arm above his head as a part of a natural movement while jumping and because the player was unable to see the ball coming from his back. Therefore the correct decision would have been letting the play go on.
87 % of the voters in the poll have disagreed with this interpretation - including me. A further post on this current issue in refereeing will follow in due course.