Detectives have released details about clues uncovered in the hunt for armed robbers who stole about £1m after hijacking a security van.
Police said the robbers who tied up a security guard and drove the Securicor van six miles before abandoning it dumped the cash on a roadside bank.
It was then picked up and switched to another vehicle, police believe.
The robbery happened on Tuesday at about 0900 GMT when the van and guards had stopped off at Fitzalan Road in Horsham.
Police said the van was driven to Faygate after one of the guards was tied up in the back and the other held in the front.
Detectives have now said the money was dumped on the bank in Faygate Lane a short way from where the van was abandoned.
When the van stopped so the money could be dropped off, a white saloon car pulled up right behind it and also stopped.
Then a white Nissan open back truck overtook both stationary vehicles and stopped a short way up the lane.
Detective Inspector Steve Johns, said: "I am very keen to speak to the driver of the truck as he may have some significant information."
The robbery was carried out by a man dressed in a helmet and jacket like those worn by Securicor staff, police said.
He is described as a black man, in his 20s, 6 ft tall and well-built.
One of the two guards in the van suffered bruising to the face but Securicor said both were extremely shaken by the ordeal.
They managed to raise the alarm after the van was abandoned.
The vehicle was recovered and has been examined by police forensic experts.
Officers believe a green S-registration hatchback-style 216 series Rover may have also been used by the robbers.
A £100,000 reward has been offered by Securicor for information about the raid.
Anyone with information should contact Sussex Police and quote Operation Rattle.