Two men have been arrested in connection with the murder of Raymond Johnston in west Belfast last week.
The 27 year old and 47 year-old were arrested under the Terrorism Act.
Two other men arrested earlier this week, aged 57 and 34, have been released unconditionally.
Mr Johnston (28) was shot dead in the house he shared with his partner and her 11-year-old daughter in Poleglass.
A shotgun was used in the February 13 attack in the Glenbawn Avenue home.
