Last Sunday, Hamel sat in the video room as a referee for the Paris Saint-Germain–Auxerre match, and a few days earlier he was the main referee between Lille and Rennes.
Now he is dead.
This was announced by the French referees' association SAFE through its channels.
"The judges are in mourning.
We learn that our colleague and friend, Johan Hamel, Ligue 1 referee, has passed away at the age of 42.
To his family, relatives and friends, SAFE and the judges send their deepest condolences.
Johan, we will miss you," they write.
As recently as November 2, he was the fourth official between Real Madrid and Celtic in the Champions League, and he has previously refereed many international matches in the major European tournaments.
In Ligue 1, there were a total of 135 games for Hamel.
Several clubs and players in France have issued their condolences on social media.