Dortmund police have said an officer is under investigation because of suspected "undue use of pepper spray" against Tottenham Hotspur supporters trying to enter the Westfalenstadion last Thursday.
Seventeen Spurs fans suffered irritation to their eyes after police used pepper spray outside the ground before the first leg of the teams' Europa League round-of-16 tie, which Dortmund won 3-0.
Dortmund police said in a press statement on the night of the match that spectators' late arrival at the ground had "led to an exertion of pressure on the gates," which resulted in "some 80 supporters" entering the stadium "uncontrolled."
That prompted the authorities to temporarily close the gates and, after they were reopened, there were "conflicts between visiting fans and security," according to the statement.
On Wednesday, Dortmund police released the results of their investigations into the incident.
Although they reiterated that some Spurs supporters arrived at the stadium too late, they said "investigations so far" had led to "the reasonable suspicion" against the officer of "the undue use of pepper spray."
Tottenham said it was "completely unnecessary and unacceptable" for police to use pepper spray, accusing the authorities of creating "a potentially dangerous situation."