The alleged scam occurred when Yadav was Railway Minister between 2004 and 2009. Apart from the RJD leader, the chargesheet also includes the name of the then Railway General Manager.
On last Sunday, Sisodia requested the central agency to defer questioning saying that he is "preparing the budget" at present and can only appear before it towards February-end.
After the AAP took office in Delhi in 2015, the CBI claimed in its report that a spying unit led by Manish Sisodia had been established. The CBI report was deemed politically motivated by the AAP, who denied the accusations.