Police in the North are continuing to question three men and woman arrested yesterday in connection with the murder of Daniel McGurk in west Belfast.
The 35-year-old father-of-six was shot dead in front of his family at his home in the Lower Falls area on Sunday.
Dissident republicans have been blamed for the killing.
Mr McGurk had been beaten up by a gang earlier last week after urinating outside the house of a dissident republican in the Lower Falls area.
His mother said her son was killed because he stood up to "thugs and drug dealers".