Gardaí are waiting for doctors' clearance before interviewing a man who they believe shot himself accidentally shortly after a young mother was shot and seriously wounded in the Bluebell area of Dublin.
The double shooting occurred at a flat complex in Dublin 8 just after 1pm on Saturday.
Mother-of-one Sinéad Connolly (30) was hit in the chest and arm and is in an extremely serious condition in hospital.
Later that same day a man presented himself to hospital with serious gunshot wounds. He remains in hospital in a serious but non-life threatening condition, sources said.
Four men, aged in their 20s and 30s have already been arrested in relation to the incident. Three are from Northern Ireland and one is from Dublin.
Three were released on Sunday and one remains in custody under section 30 of the Offences against the State Act, anti-terrorism legislation which permits him to be held for 72 hours. One of the released men is a close relative of a prominent dissident republican in Northern Ireland.
The man in hospital has not been arrested. Gardaí wish to speak to him but must wait until his condition improves.
The Special Detective Unit is assisting in the investigation. Over the weekend the scene was forensically examined and extensive door-to-door inquiries were carried out.
Initial Garda inquiries indicate a group of men with links to dissident republican groups came down from Northern Ireland to threaten or intimidate a Dublin man. This man then fired at the group but hit Ms Connolly instead. Her eight-year-old daughter was in the flat when she was shot.
Ms Connolly is the younger sister of Seán Connolly (41), a member of the Real IRA paramilitary group who is serving a life sentence for the murder of Dublin drug dealer Eamon Kelly in 2012.
Kelly was killed in revenge for the murder of Alan Ryan, a Dublin Real IRA leader, earlier that year.
However Ms Connolly is not involved in criminality and gardaí believe she was not the intended target of the gunshots.
Ms Connolly was hit in the chest and in the arm as she stood in her flat in Bernard Curtis House. She was rushed to St James's Hospital where she underwent emergency surgery. Gardaí are eager to speak with her but may not be able to for some time, sources said.
At some point shortly after the shooting, a man shot himself with the same gun used to shoot Ms Connolly. Later that day he also presented at St James’s seeking treatment.
Garda sources say further arrests are expected in the case.
The Garda said in a statement that anyone with any information in relation to this incident “should contact Kevin Street Garda station on 01 666 9400, the Garda Confidential Line on 1800 666 111 or any Garda station.”