The 2.Bundesliga club, who are currently first in their division and on course for a promotion to the Bundesliga received a letter earlier in the year issuing death threats to Bayern Munich stars Lewandowski, Neuer and Gnabry.
The author of the letter named the three stars as “dirty Bavarian pigs” and called for them to be shot to death.
German newspaper BILD reports that the letter was delivered to the offices of St Pauli on January 12. The Hamburg-based club have since turned the letter in to the police in Hamburg who are examining the note for fingerprints and DNA traces.
Bayern Munich, as well as the officials of the Bundesliga and German football in general, have also been put on high alert.
The letter was titled: “Save the league, save football. Fire and death to the dirty Bavarian pigs” and also had threats for some Bundesliga referees from the author.
A police spokesman, Florian Abbenseth, told BILD: “We are investigating on suspicion of threatening and disturbing the public peace by threatening to commit crimes. We will check the backgrounds.”
The German State Criminal Police Office (LKA) have also put out a notice across the country for all officers and departments to be on the lookout for any such letters and suspicious movement in and around football venues in the country.
The DFB (German Football Association) and Bayern Munich have yet to make any comment thus far.