The 10th grade ‘MSA' final math took place on Wednesday, but authorities believe someone leaked the test up to two weeks earlier, according to Berlin daily Berliner Morgenpost on Friday.
“It was sold in the school yards,” spokesperson for the education administration Kenneth Frisse told the paper.
An unnamed student told the paper that the test questions were sold for €10 to €15.
Authorities don't know just how widespread the cheating was, but education senator Jürgen Zöllner believes it was enough to warrant a criminal investigation, the paper reported.
“But probably none of the teachers noticed a thing,” Zöllner said.
Education spokesman Frisse told the paper it's likely that someone involved in the test's preparation is the culprit.
Zöllner told Berliner Morgenpost that the first report of the massive cheating scandal came in around 9:55 am on Wednesday, but authorities did not discover the extent of the cheating ring until after the students had taken the test.
Test results have been declared invalid, and a new test date set for June 23, but many students feel it's unfair they have to go through the stress of final exams twice, especially if they weren't among the cheaters, the paper reported.
Students plan to protest the second test on Monday in front of the Berlin's city council building, the Rotes Rathaus.
Frisse has asked anyone with information on the source of the leak to contact police in their ongoing investigation.