A fourth man has been arrested in connection with the murder of 28-year-old James Mc Donagh in Toomebridge.
Mr McDonagh from Castledawson died after he was assaulted outside the Elk bar and nightclub complex on the Hillhead Road on Sunday morning.
The 41-year-old was arrested in Toomebridge on Monday night on suspicion of murder.
A PSNI spokesman said he was being questioned in Musgrave Street PSNI station.
A 20-year-old man arrested on Sunday night has been released on bail pending further inquiries.
Two other men - aged 24-years and 53-years - remain in custody.
Police are appealing for anyone with information about the incident to contact them on 101.