Gardaí in Buncrana have renewed their appeal following a crash in the Ardmore area of Muff on Sunday afternoon.
The accident occurred between two cars and a motorbike shortly after 2pm.
The male, who is in his 20s, was transported to Altnalgelvin Hospital (Derry) and transferred to the Royal Victoria Hospital in Belfast for treatment after receiving head injuries during the crash.
It is understood his injuries are not life-threatening at this time.
Investigations into the crash are ongoing by Gardaí.
If you have any information and have yet to come forward don’t delay any longer, please contact the incident room at Buncrana on 074 93 20540 or use the Confidential line 1800 666 111.