Seven people are being questioned by detectives over the gangland-style killing of a man almost a year ago.
Stephen Byrne was shot in the head and chest in Sheriff Street in Dublin's north inner city last July.
The seven - five men and two women - were arrested in the north inner city area on Wednesday morning and are being held at a number of garda stations around the capital.
Four men - two in their 20s, one in his 30s and one in his 50s - and two women in their late 20s and early 30s are being detained under Section 30 of the Offences against the State Act.
They can be questioned for up to three days.
Another man, in his late teens, is being held under Section 50 of the Criminal Justice Act and can be quizzed by detectives for seven days.
The arrests bring to 13 the number of people questioned over the murder although nobody has yet been charged.
Gardai said the gangland-style gun attack happened at about 4.45pm on July 13 on the corner of Lower Sheriff Street and St Laurence O'Toole's Place - yards from a women's centre and church and a stone's throw from the city's financial district.
The gunman, dressed in black, and wearing gloves, shot the 32-year-old in the head and chest before riding off on a bike.