DC John Richmond, 43, who spent four months viewing CCTV footage, was giving evidence at the trial of 30-year-old Ross Monaghan, who denies murdering Mr Carroll by gunning him down at the Asda car park in Robroyston, Glasgow, on January 13, 2010.
The jury at the High Court in Glasgow was shown footage of the gunmen’s VW Golf arriving at Asda in Robroyston, Glasgow at 13.23 and 23 seconds and parking across Mr Carroll’s black Audi A3.
Someone is seen getting out of the rear passenger door of the Golf and then getting back in and the car drive away at 13.23 and 42 seconds.
Inside the store shoppers who were on their way out the exit are heading back into the store.
The 10 men and five women were also shown CCTV clips which showed Mr Carroll’s last journey from Lennoxtown to Asda.
Advocate depute Iain McSporran, prosecuting, also asked DC Richmond if he had arrested Monaghan on July 30, 2010 and charged him with murder and he replied: “Yes.”
The court heard that police – including firearms officers – arrived at the door of his home in Penilee at 4am.
Under cross-examination defence QC Derek Ogg asked: “When you went to arrest Ross Monaghan were there firearms experts there?” and he replied: “Yes.”
DC Richmond was then asked if any forensic experts had attended and was told: “No.”
Mr Ogg then asked: “Was Mr Monaghan’s long-tern partner there,” and replied: Yes.”
The defence QC added: “Was it felt prudent to have an ambulance in attendance,” and DC Richmond said: “Yes.”
It is alleged that while masked and acting with others, Monaghan murdered 29-year-old Mr Carroll by repeatedly discharged loaded handguns at him, shooting him on the head and body.
Monaghan is accused of - while acting with others - attempting to defeat the ends of justice by disposing of a revolver, pistol and ammunition within undergrowth in Coatbridge and Airdrie.
It is also claimed a car – bearing false number platess YF 55 EZZ – was set on fire.
Monaghan also faces a number of firearms charges.
He denies all the charges against him and has lodged a special defence of incrimination against eight people.
The trial before judge Lord Brailsford continues.