The biggest French cash robbery in recent years was a non-violent affair: Tony Musulin, a security guard, simply drove off with the money while his two colleagues were inside their office.

Police found the empty vehicle, which belongs to the Swedish security firm Loomis, two hours later. Its satellite tracking system and telephone link had been switched off and its contents, 49 large sacks of banknotes totalling € 11 million (£10 million), were missing.

Police were still at a loss for clues last night, 24 hours after Mr Musulin and the cash vanished. It emerged last night that the driver, who earned £20,000 a year, had recently bought a Ferrari sports car and had been questioned in the 1990s by police in a drug-dealing investigation.

Mr Musulin, who had a normal employment record in his decade with Loomis, had collected the cash. He stayed at the wheel while his two co-workers went inside. When they emerged, he had gone, police said.

Police initially suspected that robbers may have taken the driver hostage. However, they said they had found signs that Mr Musulin, 39, had planned the robbery carefully. “We went to search this lad’s home and were surprised to discover a flat that was almost unoccupied. It was cleaned up as if he had prepared his flight,” Xavier Richaud, the Lyons prosecutor, said. “Of course, we suspect the driver.” The suspect was unmarried and had no children, he said.

One of Mr Musulin’s colleagues told reporters that he was “slightly odd, always griping and complaining” about being badly paid. “He said that sooner or later the bosses are going to pay for this.” Mr Musulin’s picture was distributed yesterday to frontiers and airports. Lyons is a short drive from Switzerland. The Italian and German frontiers are not far away.

Police are trying to find out if there were any accomplices to the robbery inside or outside the company.

One of the puzzles is how the robber opened the security locks on the van, because at least two employees are required for the procedure. Loomis containers for the notes had been protected by devices that stain the banknotes with indelible dye in the event of a robbery.

Recent robberies of armoured vans in France have usually been violent, with thieves sometimes using military weapons such as rocket-propelled grenades.

In 2007 a dozen men used explosives to hold up a van and steal € 10 million. They had accomplices in the security company. In August last year three men forced a van guard to hand over € 7 million.

Times Recommends

• 'New York has lost its edge'
• Copenhagen will fail – and quite right too
• More than 17,000 new underwater species found