The case was registered in 2005. The agency is going to file the chargesheet within a week.

Sources in the agency said they have collected all evidence into the Rs 1000-crore scam.

An official said: “We have got all documents related to properties, submitted in various authorities, bank papers, and forged papers from the accused. Now is the right time to file the chargesheets.”

Singh was arrested from his farmhouse in Vasant Kunj in September after the agency felt that he was influencing witnesses. He is currently out on bail.

The CBI had also arrested KM Khandelwal, a contractor with the Noida Authority, and his brother BP Khandelwal, former chairman of CBSE, in the case.

Singh allegedly acquired 85 immovable properties and 100 bank accounts in Delhi, Noida, Greater Noida, Lucknow, Ghaziabad, Behraich and Nainital.

“He had eight properties in prime areas of Delhi and Lucknow which he had transferred in the names of his daughters,” said an official.

In fact, most of his immovable assets are acquired in the names of his family members, relatives, friends and some private limited companies, say officials. But the promoters and directors of these companies are his friends and family members.

“The details of a large number deposits in the 100 bank accounts and investments in shares, debentures and luxury vehicles have also been recovered,” said an official.

The CBI found that Singh was also responsible for large-scale forgery of documents, to procure these properties. “He had even forged the signature of his father to open a bank account and had deposited illegally earned money there,” the official said.

Singh was chief secretary during the Mulayam Singh government. A 1967 batch IAS officer, he had retired in 2003. He had held various sensitive positions in the state government and was also with the Central government for a while.