A 19-year-old man has been arrested on suspicion of murder after a man was killed in Derry.
Another two men, aged 26 and 31, remain in custody after they were arrested on the same charge on Sunday.
Detectives have been granted an additional 36 hours to question a 35-year-old woman who was also arrested on suspicion of murder on Sunday.
Edward Meenan, 52, was discovered off Creggan Street in Derry in the early hours of Sunday.
A 51-year-old man, who was arrested on Sunday in connection with the murder, has been released on bail pending further inquiries.
The Police Service of Northern Ireland said Mr Meenan had sustained "significant" head and body injuries.
Detective Chief Inspector John Caldwell, who is leading the investigation, appealed for witnesses to come forward and speak to police.
"I would like to hear from anyone who was in the Creggan Street or Little Diamond area of the city late on Saturday night or early on Sunday morning and who witnessed anything, or anyone who has any information that can assist with my investigation to contact detectives on 101 quoting reference 244 of 25/11/18," he said.
The chair of the Derry and Strabane policing and community safety partnership, Alderman Mary Hamilton, condemned the murder.
"I am saddened and shocked at the murder of a man that took place in the city over the weekend," she said.
"My thoughts are with the family and friends of the man and the community living in the Creggan Street and Little Diamond area.
"I would urge anyone with information on the murder to contact the PSNI or Crimestoppers immediately."