Crime journalist Paul Williams says he believes there will be retaliation for murder of Alan Ryan.
The 32-year-old was shot dead on Monday in Clongriffin in Dublin.
It's understood Gardai are investigating an intelligence report indicating that a hit man was hired from abroad to carry out the murder.
It's reported he was walking along a quiet street with two Sligo-based friends when he was targeted.
One of the men from Sligo was shot in the leg while it's claimed the second Sligo man escaped injury.
Paul Williams says the Sligo man involved in the incident was not the intended target.