Nigeria, Jan. 30 -- In 2010, while Nigerian pensioners queued endlessly for unpaid benefits, Abdulrasheed Maina was quietly shopping for homes in the United States. In August that same year, the man who was then entrusted by the Nigerian government to clean up a corruption-ridden pension system walked into a Kentucky real estate office and bought a $215,000 house.

But that purchase was only the start. Between 2010 and 2013, while serving as chairman of the Presidential Task Force on Pension Reforms, Mr Maina purchased two more houses in Kentucky and one in the United Arab Emirates, soon after he was removed from office.

The Nigerian government accused him of siphoning millions of dollars from the pension fund he was meant to safeguard d...