There had been speculation of an even greater sum of money, with 70 million kronor named, but investigators have ruled out the sum which was based on the offer of a reward from security firm G4S of 7 million kronor - 10 percent being the accepted reward sum.
The prosecutor in the case has confirmed to news agency TT that the robbers were forced to leave large amounts of cash behind as they were short on time and their helicopter was only able to carry the smaller amount.
Prosecutor Leif Görts, one of two working on the case, was unwilling to confirm the reports of the amount of cash seized.
"It could harm the investigation," Görts told TT.
A further man has been arrested in connection with involvement in the audacious heist in September 2009. The 36-year-old is suspected of aiding and abetting an aggravated robbery and aggravated money-laundering.
According to the Aftonbladet daily, the man had responsibility for processing some of the money seized. He denies the offence.
A further nine people are in custody on suspicion of involvement in the robbery.
The Västberga cash depot was hit in the early hours of Wednesday September 23rd when several powerful explosions were heard.
A helicopter landed on the roof of the depot, managed by the G4S security firm, and men entered the building to seize a large quantity of cash. The robbers then made their escape in the helicopter with the police looking on.
Police helicopters had meanwhile been grounded due to a bomb scare - the gang had left a bag with the word BOMB inscribed on the side at the helicopter station on Värmdö in eastern Stockholm.