Four people have been sentenced to prison and received tens of millions of dollars in fines for buying discounted Microsoft software and then illegally reselling it at a profit.

Mirza Ali, 60, and Sameena Ali, 53, the husband-and-wife owners of Samtech Research, were sentenced to five years in prison and ordered to pay more than $25m in fines to Microsoft for their role in a software reselling scheme run between 1997 and 2001.

The Alis and their associates purchased more than $29m worth of software at Microsoft's academic-discount rates and then resold it to non-academic entities, making more than $5m in profits. The two were convicted on 28 November, 2006 and had been awaiting sentencing.

Previous to this, the Alis had already been kicked out of Microsoft's AER (Authorized Education Reseller) programme, but they "formed new corporations... to disguise their identity from Microsoft and re-enter the AER programme", the US Department of Justice said.

They laundered their profits by purchasing real estate in their son's name and by wiring more than $300,000 to Pakistan, the DOJ said.

Two of the Alis associates, Keith Griffen, 56, and William Glushenko, 66, were also sentenced in connection with the case. Griffen, a partner in some of the Alis' corporations, was sentenced to 33 months in prison and $20m in fines. Glushenko was given one year of probation and 100 hours of community service.

The scam was exposed during the course of a two-year undercover investigation called 'Operation Cyberstorm', which was conducted by the Federal Bureau of Investigation and the US Internal Revenue Service.