Witnesses said he fired a series of shots then walked back towards the centre's car park.Police are also appealing for information about the 'potentially important' sighting of a man sitting in a white Renault Kangoo van in Clifton Country Park two days before the shooting.
Paul Massey predicted his murder nearly 20 years before he was gunned down.
You fire up the engine, increasingly electric or electric hybrid, and then set the programme for autonomous driving, activating a range of cameras, laser and radar sensors fitted throughout the vehicle — these are the ‘eyes’ feeding information back to the ‘brain’ or the onboard computer.
A simple button on the steering wheel allows you to click in and out of self-drive mode.
The man, seen at about 7pm on Friday, July 24, is described as white, in his late 30s to early 40s, about 5ft 10in tall and wearing a black hat, jacket, camouflage trousers and carrying a torch and a gun described as being the same style as an Uzi.
Father-of-five and grandfather Mr Massey was a well-known figure in his home city of Salford and had been involved with security firms operating in Manchester and beyond.
He had first been dubbed 'Mr Big' by the late Salford councillor Joe Burrows at a town hall meeting to discuss civil disturbances in 1992.