Bundesliga club Koln has encouraged fans to send photos and video clips to a special police 'evidence portal' and help them identify the trouble causers that were responsible for the violence that played out ahead of a Europa Conference League game away at Nice this week.
As a result of clashes at the French outfit's Allianz Riviera stadium, 32 people were injured including two police officers and a steward and kick off was delayed by almost an hour.
With French prosecutors launching an investigation, UEFA has opened a disciplinary case which contains eight charges against Nice and three against Koln.
As confirmed by the west German club, police in Koln have established an 'evidence portal' where photos or videos of incidents can be uploaded.
"On both sides, it was a small minority of under 100 people who caused the violent events to transpire within the stadium," insisted Koln's managing director Christian Keller.
"More than 7,900 of the 8,000 FC fans had nothing to do with the violence," he added, though Koln's traveling contingent are said to have started the trouble.
Keller remarked that the violent scenes were "particularly regrettable" because the German side had pointed out "risks and gaps" in the local authorities' security plan ahead of the match which finished 1-1.
"Unfortunately, these warnings, which had not been heeded, were confirmed during the course of the day, when French hooligans attacked FC Koln fans in the city and around the stadium," Keller claimed.
Defending his corner, French government regional administrator Bernard Gonzalez pointed out that German fans began drinking alcohol early on Thursday morning in bars in downtown Nice.
While those "most at risk" should have been placed in a secure part of the Allianz Riviera, they managed to break free to join some Parisian hooligans and sparked the violence Gonzalez also said.
Ligue 1 giants Paris Saint-Germain condemned the violence once it emerged that fans representing a banned group of ultras played a part in the confrontations.
This weekend, Nice return to action with a Ligue 1 match away at Ajaccio while Koln host Union Berlin at home.