A man arrested yesterday by police investigating a serious assault in Galliagh has been released on bail.
Police said the 37-year-old was released on bail pending further enquiries.
The victim of the attack was last night in a stable condition in hospital after being subjected to a serious assault in the Bloomfield Park area.
Detectives yesterday issued an appeal for witnesses following the incident, which occurred in the in the early hours of Monday morning.
A PSNI spokesman said: “Shortly before 6.30am it was reported that a man aged in his 50s had been the victim of a serious assault in the area.
“He was taken to hospital for treatment for a serious head injury.”
A spokeswoman for the Western Health and Social Care Trust confirmed yesterday that the man was a in a stable condition at Altnagelvin Hospital.
Meanwhile Detective Inspector Conor McStravick, who is spearheading the investigation, has appealed for anyone who was in the area of Bloomfield Park early on Monday morning and who witnessed the assault to come forward.
Det Insp McStravick further appealed for anyone with any information that could assist with the investigation to contact Detectives in Strand Road on the non-emergency number 101.
Information can also be passed anonymously via the independent charity Crimestoppers on 0800 555 111.