Kickoff in the game was delayed by an hour last Thursday following major disturbances outside the Emirates as thousands of ticketless Koln fans allegedly attempted to gain access to the ground.
Around 20,000 German fans are thought to have travelled to London for their side's first European outing in 20 years, despite the official away allocation sitting at just 2,900.
Both clubs were charged by UEFA after the match, which the Gunners won 3-1, with the Bundesliga outfit's fans being accused of crowd disturbance, acts of damage, throwing of objects and setting off fireworks.
In a statement today, UEFA has said that it has decided to appoint an 'ethics and disciplinary inspector', who will be tasked with 'evaluating the scope of both clubs' respective responsibility' over the various incidents.
If found guilty, the clubs could face significant fines and/or be forced to play future European games behind closed doors.
Gunners manager Arsene Wenger has said that it would be "wrong" for his side to receive punishment for the actions of Koln fans, while the German side have hit out at Arsenal for having "inadequate" security management in place to deal with their unruly supporters.