I am looking forward to the roundabout too! Weren't the police timing vehicle driving times, closing the round about at night and seeking witnesses of vehicles?
Is it a possible scenario that A & G have argued outside, struggled (maybe fallen hence the plant matter) and she has made a dash for the Captiva to get away from him and taken off. Gerard follows in hot pursuit in the the Prado(squealing wheels, loud thumps of car doors being slammed). If I remember a witness saw 2 cars following each other closely out near the bridge.
Another struggle at the bridge (scratches etc) and she strikes her face against the perhaps open tailgate of the Captiva? Explains the chipped tooth and perhaps a blood nose.. They bleed copiously. But his blow has killed her.
Now he has more problems on his hands. He has to dispose of the body but in addition he has two cars out at the bridge. He needs someone else to drive one of them back.
Enter NBC. After a call from G, he drives to the shopping center at the rounabout, leaves his own car there, and GBC picks him up in his Prado. Back out to the bridge, make sure the body is hidden, and they drive the two cars back to the Brookfield house. Leave the Captiva, back to the shopping center carpark in the Prado and pick up GBCs car and back to Brookfield to start inventing the night to explain the events to the police.
Too far fetched?
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