Image source, Pacemaker
Image caption, Det Ch Insp John Caldwell has been involved in high-profile investigations into dissident republican attacks
By Jayne McCormack & Ross McKee
BBC News NI political correspondent
A fourth man has been arrested over the attempted murder of an off-duty detective chief inspector in Northern Ireland.
Two gunmen shot John Caldwell several times as he was putting footballs into his car with his son after an under-15 training session in Omagh, County Tyrone, on Wednesday.
The 48-year-old remains in a critical but stable condition in hospital.
Political leaders will meet the chief constable later to discuss the attack.
The police investigation is looking at dissident republicans, with a focus on the New IRA, but PSNI Assistant Chief Constable Mark McEwan said police were keeping an open mind.
On Friday morning, the Police Service of Northern Ireland (PSNI) said a 22-year-old man had been arrested in the Coalisland area of County Tyrone under the Terrorism Act and is currently being questioned at Musgrave Serious Crime Suite.
Three men – aged 38, 45, and 47 – arrested in Omagh and Coalisland on Thursday – remain in custody.
Det Ch Insp Caldwell is one of the best-known detectives in the PSNI, often fronting press conferences on major inquiries during his 26-year career.
The father-of-four had coached a Beragh Swifts training session at Youth Sport Omagh when the gunmen approached and shot him at about 20:00 GMT on Wednesday.
Children ran in terror when the shots rang out in the car park, and Beragh Swifts chairman Ricky Lyons said the club was supporting the young players who witnessed the shooting.
“He was taking a kids’ training session – it’s hard to compute that someone would try to attempt to kill John at that moment,” said Mr Lyons.
Irish Football Association (IFA) President Conrad Kirkwood said he had received a message from Det Ch Insp Caldwell earlier this week about hosting a football seminar at his club.
“This is a guy who, despite having a busy day job, is absolutely invested in trying to make things better – it makes it even more tragic,” he added.
A police cordon at the scene of the shooting at the Youth Sport Omagh complex has been reduced on Friday morning, but remains in place.
A recovery vehicle carrying two cars left the scene under police escort on Thursday night.
Terrorism threat level scrutinised
Politicians have condemned Wednesday’s attack as reprehensible and callous.
Representatives from the Policing Board, which includes assembly members from the five main Stormont parties, were briefed by PSNI Chief Constable Simon Byrne on Thursday.
Image source, PA
Image caption, PSNI Chief Constable Simon Byrne will meet the parties later
Sinn Féin deputy leader Michelle O’Neill said politicians from her party, the Democratic Unionist Party, Alliance, Ulster Unionist Party and Social Democratic and Labour Party would discuss Northern Ireland’s current terrorism threat level when they meet Mr Byrne later on Friday.
A rally to condemn the attack will be held at Omagh’s courthouse on Saturday morning.
It will take place close to where 29 people died after a bombing in the County Tyrone town on 15 August 1998 – the biggest single atrocity in the Troubles.
Last March, the the threat level posed by dissident republican terrorism in Northern Ireland was lowered from severe to substantial for the first time in 12 years.
The decision to lower the threat level was taken by the Security Service (MI5) after assessing a wide range of information, independently of ministers.
Since 2010 it had been “severe”, meaning attacks are highly likely. It is now “substantial”, meaning attacks are likely.
The threat level is assessed over a period of time rather than in reaction to one event.
Dt Ch Insp Caldwell has been the senior detective in high-profile inquiries including:
He had received a number of threats in the past, BBC News NI understands, and was aware his investigations of dissident republican attacks made him a high-profile target.
He continued to carry out his activities as a football coach and whether that was a pattern that aided the targeting of him is of course a matter for the investigation.
Police believe the gunmen made off in a small, dark car, which was found burnt out at Racolpa Road, outside Omagh.
The Racolpa Road is closed between the Rushill Road and Crocknacor Road. On Friday morning, police confirmed this is connected to the investigation.
An Garda Síochána (Irish police) said it had intensified patrolling in border counties.
Image source, Jason McCartan
Image caption, This car at near a farmyard on the Racolpa Road outside Omagh is thought to have been used by the gunmen and was later burnt out
The last gun attack on a PSNI officer was in January 2017.
The PSNI officer was hit by automatic gunfire at a petrol station in north Belfast.
Who are dissident republicans?
The term “dissident republicans” describes a range of individuals who do not accept the Good Friday Agreement – the 1998 peace deal that ended the worst of the Troubles in Northern Ireland.
The Provisional IRA – the main armed republican paramilitary group for most of the Troubles – declared a ceasefire in the run-up to the agreement and officially ended its violent campaign in 2005.
Dissident republicanism is made up of various groups which broke away from the Provisional IRA in the 1980s, 1990s and 2000s, including the Continuity IRA and New IRA.
They have continued to use violence to attempt to unite Northern Ireland with the Republic of Ireland in a single state, but their activities have been sporadic and often undermined by the security services.
While much smaller than the Provisional IRA, the groups have access to high-calibre weapons and have used improvised explosive devices and mortars in attacks and attempted attacks.
The biggest and most active group is the New IRA, which is strongest in Londonderry and County Tyrone.
Previous security assessments estimated it had about 100 members prepared to commit violent acts, and about 500 supporters.
It has been put on the back foot by several successful security operations run by MI5, leading to the 2022 terrorist threat level reduction.
But after a lull in activity the New IRA re-emerged in November with a bomb attack on a police patrol car.