Singh has come under scanner for allegedly bypassing rules and regulations for granting licenses for sand mining during his tenure as District Magistrate of Fatehpur in 2012.
The officials said cash of around Rs 47 lakh was recovered from the premises of Singh and they had to bring in a note-counting machine to count the total amount of cash.
CBI team arrived at the residence of Singh who is now the DM of Bulandshahar, early Wednesday morning and questioned him for about two hours.
The probe agency conducted searches at 12 locations in Uttar Pradesh including Deoria, Gorakhpur and Lucknow.
The agency also conducted raid at the premises of 2009-batch IAS officer Vivek, the mission director of Uttar Pradesh Skill Development Mission, after registering FIRs against both the IAS officers.
The CBI is currently said to be investigating the charges of illegal mining in five districts of Uttar Pradesh - Shamli, Hamirpur, Fatehpur, Siddharthnagar, and Deoria.
In January, (CBI) registered a case against IAS officer B Chandrakala who was the district magistrate of Hamirpur during 2012-14 when she allegedly violated e-tender system of allotting mining contracts in her district.
The CBI took up the matter on the directions of the Allahabad High Court in the year 2017. It was directed to investigate the matter after a plea was filed alleging that illegal mining was taking place in the state with involvement of government authorities as well.