Three men have been arrested as part of the investigation into the murder of Christopher Warren.
The 36-year-old was shot dead at the Royal Canal in North Dublin on December 28 last year.
Two men, aged in their 20s, are being held under Section 50 of the Criminal Justice Act, while a third man in his 60s is being detained under Section 30 of the Offences against the State Act, at garda stations on Dublin's north side.
Today's arrests bring to five the number of people detained in relation to the murder investigation.