Calcutta police commissioner Rajeev Kumar had tampered with the call detail record of an accused in a chit fund case and suppressed facts before the CBI, the central agency alleged in an affidavit submitted to the Supreme Court on Tuesday.

By levelling the charges of tampering with evidence and suppression of facts, sources said, the CBI was trying to malign the Bengal-cadre officer and prove his alleged nexus with the Trinamul Congress.

CBI officers said that through the affidavit, they had submitted the gist of their findings. “We will submit all supporting evidence in closed envelopes during the course of the hearing in the Supreme Court. Today, we just submitted the gist of our investigation and findings against the officer concerned,” a CBI officer said.

After the hearing on Tuesday, the court passed an order asking Kumar to “co-operate” with the CBI while restricting the agency from taking “coercive action” against him.

A senior lawyer in Calcutta not involved in the chit fund cases said: “It would be the duty of the CBI to prove every word mentioned in the affidavit, more so because the allegations are not just against a respectable individual but the head of another premier institution. Failure to prove the allegations may attract legal recourse in the form of a defamatory suit against the CBI or a counter-affidavit for submission of a false statement to the Supreme Court.”

The CBI’s affidavit mentions that as the head of a special team entrusted by the Bengal government to probe multiple default scams, such as Saradha and Rose Valley, Kumar was responsible for the day-to-day monitoring of the investigations.

According to the affidavit, Kumar withheld the call detail record of an accused in connection with a chit fund case for four years and handed over a “doctored” document to the central agency only last year.

“The CBI was entrusted with the investigation (of the Saradha scam) on May 9, 2014. Rajeev Kumar was not parting with the investigation material containing the evidence collected by the special investigating team headed by him clearly in connivance with the main accused persons. In spite of the continuous insistence and follow-up by the CBI, he furnished only CDRs of the prime accused only on June 28, 2018,” the affidavit reads.

The CBI claimed in the affidavit that the agency had directly got hold of the CDR from a telecom service provider and upon comparison, it was found that the one submitted by Kumar was doctored.

Sources in the CBI alleged that Kumar, as the head of the SIT, was also responsible for “suppression of facts” by not informing the central agency about the presence of an FIR against the Rose Valley Group in Bengal.

“There was an FIR dated October 4, 2013, in Durgapur police station against M/s Rose Valley and the same was suppressed by the SIT, functionally headed by said Rajeev Kumar, IPS. It is submitted that the said suppression resulted in non-registration of RC against M/s Rose Valley in the State of WB. It is submitted that in light of the same, the CBI sought to register RC against M/s Rose Valley in the State of Orissa and the investigation suffered.”

Without elaborating on the detailed findings of the CBI, the document mentions that there is “prima facie” evidence suggesting that Kumar committed offences under “Prevention of Corruption Act and other sections under the Indian Penal Code”.