In letters to Chief Secretary Malay Dey and Home Secretary Alapan Bandopadhyay, the federal probe agency sent copies of summons issued to Kumar asking him to appear for questioning before the CBI at 2 p.m. on Monday.
Along with the letters and copies of the summons, the CBI had also attached a copy of Friday's Calcutta High Court order withdrawing the interim protection from arrest given to Kumar, currently the Additional Director General of the Criminal investigation Department.
The CBI had in fact sent the letters to the two top bureaucrats alongwith two other missives to Director General of Police Virendra on Sunday. But while the police control room - that remains open 24x7 - accepted the letters meant for Virendra, they refused to accept the other two arguing it was a weekend holiday.
Of the two letters from the CBI to the DG, one was similar in content to those addressed to the two secretaries.
In the other letter, the federal agency asked Virendra about the leave granted to Kumar, and details about his whereabouts during the period, including his contact number. According to CBI officials, an officer of the rank of ADG is required to clearly furnish why he is availing leave, where he would be during this period, and the contact numbers to get in touch with him in case of emergency.
In somewhat identical responses, Dey, Bandopadhyay and Virendra wrote back to the CBI on Monday that Kumar was on leave from September 9-25. They said the officer has been incommunicado with his official mobile number and the mobile phone of his bodyguard switched off. They also said that the notice has been sent to Kumar's official residence at 34, Park Street.
Meanwhile, the police presence around the CBI office in Salt Lake Central Government Office complex was intensified, with a number of high ranking officers seen in vehicles outside the main gate.
The CBI officers, led by the agency's joint director Pankaj Srivastava, held a series of consultations during the day. It was learnt that the CBI has filed a caveat in the Supreme Court, thereby not giving any scope to Kumar to get any ex-parte order from the apex judiciary.
The BJP saw the state government's hand in Kumar "going underground".
"The government knows very well where Kumar is hiding. The entire administration is bent on protecting Kumar," said BJP national secretary Rahul Sinha.
The Congress said the government has no moral right to continue in office when it is "completely in the dark" about the whereabouts of such a senior officer.
( With inputs from IANS )