An appeal has been issued by The Police Ombudsman's Office for witnesses in relation to the disturbances in the Obins/Corcrain area of Portadown on 15 July 2011.
Petrol bombs and other missiles were thrown at the police, who responded with the use of Attenuated Energy Projectiles (AEPs).
The disorder began at around 21:00 hours, and the Office is looking to speak to anyone who may have witnessed what happened from this point onwards.
Investigators can be contacted on the Police Ombudsman Witness Appeal Line 0800 032 7880.