A fourth man has been arrested by police in Northern Ireland investigating the <a href="https://www.thenationalnews.com/world/uk-news/2023/02/23/omagh-shooting-police-officer-ira-northern-ireland/" target="_blank">shooting of a senior detective</a> in the town of Omagh, County Tyrone. Detective Chief Inspector John Caldwell was <a href="https://www.thenationalnews.com/tags/crime/" target="_blank">shot in front of his son</a> by two masked gunmen as he put footballs in a car after finishing a coaching session with an under-15 football team on Wednesday evening. DCI Caldwell is in a critical condition after the shooting, which has shocked the town and seen people from across the political spectrum come together to condemn the attack. The five main parties in Stormont presented a united front on Friday at a news conference led by officers from the Police Service of Northern Ireland. “We do not underestimate, from the point of view of the police service, how important it is that we are joined today in an act of unity from all the political parties across Northern Ireland,” PSNI Chief Constable Simon Byrne said. “Clearly, we know from what we've done so far and from commentary from across the community, and the political spectrum, the sheer sense of outrage of this pointless and senseless attack on Detective Chief Inspector John Caldwell. “John remains in hospital, where he is critically ill and heavily sedated. “We have arrested a further man overnight in relation to this investigation. He is now in custody and also being questioned by detectives.” DCI Caldwell has led a number of major investigations, said police. The PSNI quickly turned its attentions to the dissident republican group the New IRA as its primary focus. The New IRA has targeted police before and was responsible for the killing of journalist Lyra McKee in 2019. It is a much smaller group than the Irish Republican Army, which disarmed when the Good Friday accord ended the fighting between nationalist militants seeking unity with Ireland, and pro-British unionists wanting to stay in the UK. The UK last year lowered its Northern Ireland-related terrorism threat level for the first time in more than a decade, with police saying at the time that operations against nationalist militants were making attacks less likely.