Bayer Leverkusen centre-back Emir Spahic is the subject of a police investigation following an altercation after the club's cup match on Wednesday.
In video acquired by Bild, Spahic appeared to join in a confontation between fans and stadium stewards.
Bayer on Thurdsay confirmed that police passed their findings of the incident to the prosecutor's office, and an investigation is pending.
Club sporting director Rudi Voeller told Bild that the club "will not prejudge" Spahic's actions before the investigation has concluded.
Bayer lost to Bayern Munich on penalties. Spahic left the game with an injury in the 90th minute.
Also on Thursday, UEFA fined Bayer 20,000 euros for unsporting behaviour in their Champions League match against Atletico Madrid.
UEFA objected to a banner "with insulting remarks in Spanish aimed at Atletico fans," a club statement said.