Sources said Singh arrived at the agency headquarters in the afternoon after which he was questioned by the team probing the cases for nearly five hours. They said Singh was grilled on various aspects of the cases, projects handled by him and was also confronted with related documents.
Meanwhile, CBI has also written to Income Tax deportment seeking documents related to the case. The agency had registered two separate cases against Singh and his family members for alleged corruption and amassing assets disproportionate to the known sources of income.
CBI sources said the first case was registered under criminal conspiracy and provisions of Prevention of Corruption Act against Singh, his wife Kusum Lata, daughter Garima Bhushan and son Sunny Yadav besides one more person Rajender Minocha for amassing disproportionate assets.
The alleged disproportionate assets were discovered during searches by Income Tax department in November, 2014 in which several incriminating documents and the Income Tax Returns were recovered from several premises of Singh.
"The scrutiny of ITRs and other connecting records have allegedly revealed that during the period 2009-2014, the total likely savings of the family of then Chief Engineer was Rs 1.70 crore (approx) whereas they were in possession of immovable property worth Rs 3.60 crore (approx).
"Besides, an amount of Rs 10 crore (approx) was allegedly recovered from one of his associates, which also reportedly belonged to then Chief Engineer," CBI spokesperson had said here after registering the case.
The official had said cases have been registered on the direction of Lucknow Bench of Allahabad High Court which directed it to conduct an investigation into allegations of corruption and amassing of unaccounted money by the accused in regard to all transactions, persons and entities connected there to.
The official had said the second case relates to allegations of criminal conspiracy, cheating, forgery and provisions of Prevention of Corruption Act against Singh.