Two suspects have been arrested by gardai investigating the gangland-style murder of a man in front of his son.
Declan O'Reilly was shot dead on Dublin's South Circular Road on September 24.
A Garda spokesman said two men, both in their mid-20s, were arrested on Monday morning and taken to Kevin Street and Kilmainham Garda stations.
They can be held for up to seven days under Section 50 of the Criminal Justice Act 2007.
Gardai are investigating if the 32-year-old victim was gunned down in retaliation for stabbing a fellow inmate in Mountjoy Prison to death in September 2007.
Mr O'Reilly, a convicted criminal, was aware his life was under threat since a jury acquitted him of killing Derek Glennon after he said it was self-defence.
He survived a similar attack last year.