A car used by the gunmen who tried to kill PSNI Detective Chief Inspector John Caldwell was seen on camera in the Ardoyne area of north Belfast before being driven to Co Tyrone .
It is understood that automatic number plate recognition (ANPR) technology, which reads and retains vehicle registration plates, picked the car up in various locations before the attack on Mr Caldwell.
The car used by the gunmen was stored in Belfast and the Coalisland and Omagh areas
He was shot a number of times in front of his son at a sports complex in Omagh last Wednesday.
Of the six people still being questioned by police, two are being held specifically in relation to the purchase of the getaway car used by the two gunmen.
The blue Ford Fiesta, registration number MGZ 6242, was bought in Ballyclare, Co Antrim, and was then fitted with false plates, FRZ 8414, before the attack.
Footage of the car was released by the PSNI yesterday.
The PSNI also confirmed Mr Caldwell remains in a “critical but stable condition”.
So far, 12 searches have been carried out by the PSNI in Omagh and Coalisland.
The car used by the gunmen was stored in Belfast and the Coalisland and Omagh areas, indicating a “carefully planned” attack.
Six men, aged 22, 38, 43, 45, 47 and 71, are being questioned by police.
Detectives have until this evening to either charge or release two of the suspects.
They can also apply for a further extension to custody with terrorism legislation allowing detectives to hold them for up to 14 days without charge.
CCTV footage shows the car leaving the sports complex after the attack on Mr Caldwell and turning left on to the Killyclogher Road.
It travelled past Glendale Service Station to the Racolpa Road where it was abandoned and set on fire.
The car was bought in Ballyclare on February 8 and travelled towards north Belfast on the M2 that night.
It was caught on camera leaving Belfast at about 9.30pm last Tuesday, the night before the attack, and travelling along the M1 in the direction of Coalisland/Omagh.
Mr Caldwell was packing equipment away after a coaching session with Beragh Swifts under-15s when two gunmen approached.
The PSNI said “at least 10 shots” were fired – four hit Det Chief Insp Caldwell.
He was given first aid at the scene by a doctor who had been training at the Omagh facility
A number of bullets hit parked cars.
The gunmen, who witnesses say appeared inexperienced, dropped a number of live bullets at the scene.
Mr Caldwell is said to have shouted “run” at nearby children before running about 200 metres then falling to the ground.
He was given first aid at the scene by a doctor who had been training at the Omagh facility before being treated by paramedics and rushed to hospital.
The New IRA claimed responsibility for the shooting in a letter that was reported to have been posted on a wall in the Creggan area of Derry.
Senior investigating officer Eamon Corrigan said he is aware of the claim and it forms part of the wider police investigation.
He added: “Quite clearly this attack was carefully planned; it was planned in advance.
New IRA claimed responsibility
“A vehicle had been obtained weeks ahead of the attack on John.
“It travelled down the night before with false plates.
“I believe a number of people were involved in the plan to attack and kill John and they haven’t been successful.”