Three men in their 60s and 70s, nicknamed the "grandad robbers" by the German press, were sentenced to a total of 31 years in prison on Friday after being found guilty of a spree of bank robberies. The youngest of the group, Rudolf Richter, 64, was sentenced to 12 years in prison while 73-year-old Wilfried Ackermann received a 10-year sentence. The gang's mastermind, Lothar Ackermann, 74, was sentenced to nine years jail. The heavily armed trio had carried out 14 robberies over a 16-year period from 1988 to 2004, netting more than one million euros ($1.22 million). They kept part of their booty which they intended to use to finance their retirement. Wilfried Ackermann had told the court in the western city of Hagen: "You cannot imagine how easy it is to rob a bank when you have already done it twice before." He said he had been a criminal for much of his life and had already spent 40 years of his life in jail. He had used some of his ill-gotten gains to buy a farm. The trio were arrested in last November as they were preparing to rob a bank.