The Usual Suspects
Fortunately for the police, the gang members involved were well known to them and already under surveillance for their suspected roles in a number of unsuccessful armoured vehicle robberies. Wenham was the first to exhibit an unusual interest in the diamond display at the Dome and when partners in crime Betson and Cockram were also observed loitering around the same exhibition and taking video footage, in early September 2000, police began to suspect that the display was to become yet another of their targets.
At this point, surveillance of the men was increased substantially and the Dome itself was placed under close watch. Police were able to narrow down the number of likely days an attack might take place and the Dome management, as well as De Beers, were alerted to the likelihood of an attempted robbery. As a precaution, crystals of the same size and shape as the genuine Millennium Jewels were created, so that the real stones could be stored elsewhere.
As the surveillance net was extended, with up to 100 officers involved in the operation, the other members of the gang became known to the police, and included convicted felons Terry Millman, entrusted with procuring the getaway speedboat, Aldo Ciarrocchi, and Bob Adams, who was the last to join the gang. Kevin Meredith, the boat pilot, who did not have a criminal record, later claimed that Millman had coerced him into assisting with the heist.