Police at Strand Road in Derry are trying to establish how a man in his 50s sustained serious head injuries.
At around 10.30pm on Sunday, 23rd, the ambulance service was called to Lower Bennett Street, where a man in his mid 50s had been found unconscious. He was taken to Altnagelvin Hospital, and then transferred to the Royal Victoria Hospital.
He has remained unconscious in hospital since the weekend.
Information can be given to the CID at Strand Road on the 101 non-emergency number, quoting reference number 294 23/04/14.