I've always thought that the police caught GBC and NBC out cleaning/vacuuming the car when they arrived so quickly. Then I wavered on this when it didn't come out in the evidence. However, when i think about it, even if there HAD been leaves matching the plants at home, what would that prove? they would have said that yes, the leaves blow inside and we use the vacuum cleaner often to clean them up. You can't prove that the leaves came from the car.