The personal background of Islamic Irish convert Terence Kelly, who blew himself up in an Isis bombing attack in Iraq, is set to be studied closely by the Garda in a bid to establish if any of his associates still in Ireland pose a threat.
Kelly had spent a lot of time in the Middle East and in the UK, where his wife and three children live, but he had been residing in the Republic up to last spring.
Gardaí believe he had begun the process of committing to becoming a suicide bomber for Isis while living in Ardagh, Co Longford.
The investigation into his background will seek to establish whether he was helped by anyone in Ireland and if they might pose a threat to Ireland, especially from the UK. It will also seek to determine whether he was in touch with others on social media either trying to radicalise them or encouraging them to come to Ireland.
The Garda believes between 30 and 40 people have left Ireland to fight in trouble spots such as Iraq, Afghanistan and Syria. A small number, like Kelly, are Irish people born and raised here while others are nationalised Ireland or have been raised here in families who have come from abroad.
Suspects are being monitored in Ireland, though gardaí concede privately that there may be more foreign fighters from Ireland than those who are known about.
Garda sources added that because radicalisation and recruitment is done online and the countries so-called foreign fighters are travelling to are chaotic after years of war, getting complete information is almost impossible.
Kelly was arrested by the Garda in 2011 when he suggested US president Barack Obama should be killed when he visited the Republic.
He was released without charge at the time and the process and decision making around that turn of events will now be revisited.
He had been placed under physical and electronic surveillance in Ireland, though it was unclear what Irish security forces knew, if anything, of his time spent in Iraq in the months before he died last Friday.
He left the Republic for England, around eight months ago, and spent some time in the UK with his wife, from Pakistan, and their three children.
He then tried to travel to Syria via Turkey but was prevented from doing so after his departure from the Republic had been flagged internationally by the Garda.
There are no powers of preventative detention in Ireland meaning the Irish authorities, who had no specific intelligence about what he planned to do, could not have prevented him leaving.
After failing to get to Syria his movements were not known to the Garda or the Defence Forces, though those details should emerged now.
The 50-year-old, from The Liberties in Dublin's inner city, late on Friday drove a modified military vehicle packed with explosives into a base near Mosul used by Iraqi forces fighting Isis for control of the city.
After four years working as a nurse in Saudi Arabia he was caught brewing alcohol, for personal consumption and sale to other ex-pats, and was jailed.
He was radicalised in prison, converting to Islam and emerging from prison going by the name Khalid Kelly.
He moved to London, where his Pakistani wife and three children now live, within two years of his release but had also spent time back in Dublin. He left London in 2008 and was believed to have travelled to Pakistan to train with the Taliban, later moving back to Dublin and being watched closely by the Garda.
By 2010 he had settled in Co Cavan and later moved to Ardagh, Co Longford where had lived alone for at least the last year.
Kelly was apparently known by Isis as Abu Usama an-Irelandi. He called himself Khalid Kelly and was also known, mainly in the media, as Taliban Terry after reports emerged that he was training with the terrorist group in Pakistan in 2009.
Isis released statements on social media, along with video and photographs of the explosion in which Kelly died, saying the attack had killed and injured large numbers.
However, the Shia Popular Mobilisation Units, whose forces Kelly attacked, claimed while there had been injuries there were no fatalities.
