A man in his 20s has been arrested in connection with the shooting of Charles Sinapayen in Bray last week.
He is being questioned at Shankill Garda Station in Co Dublin.
Two men and a woman in their 20s are also in custody in connection with the investigation.
Two people questioned as part of the investigation were released last night.
A file will be prepared for the Director of Public Prosecutions.
Mr Sinapayen was shot at an apartment in Richmond Hill in Fassaroe that he shared with his partner.
The 32-year-old French man died in Beaumont Hospital on Monday from the injuries sustained in the shooting.
