The CBI on October 15 last year had registered a First Information Report against Rakesh Asthana (File)

CBI officer Satish Dagar, who was probing the corruption case against the agency's former special director Rakesh Asthana, has applied for voluntary retirement, an official said on Wednesday.

"Satish Dagar, SP, CBI has submitted application for voluntary retirement on personal grounds," CBI's spokesperson said.

The CBI on October 15 last year had registered a First Information Report against Rakesh Asthana for allegedly taking a bribe from an accused probed by him in return of ensuring relief and a clean chit in the case.

Rakesh Asthana has strongly refuted these allegations.

The then CBI director Alok Verma and his deputy Rakesh Asthana were sent on leave by the Centre through a midnight order on October 23 as both levelled allegations of corruption against each other.

Satish Dagar was brought in to probe the case by M Nageswar Rao, a 1986-batch Odisha cadre IPS officer, who took over the duties and functions of CBI director on October 23, 2018 in a dramatic midnight change in the agency's leadership made by the centre.

The case was earlier being probed by Superintendent of Police AK Bassi who was transferred to Port Blair by M Nageswar Rao.

Satish Dagar is understood to have sent his letter seeking voluntary retirement last month, sources said.

Senior officials have made efforts to persuade him to reconsider his decision but he has so far refused, they said.

After taking over on October 23, M Nageswar Rao had overhauled the team probing allegations of corruption against Rakesh Asthana, bringing in completely new faces.

While Satish Dagar, who had earlier probed cases against Dera Sachcha Sauda chief Gurmeet Ram Rahim, was deputed as investigation officer, his first supervisor was Deputy Inspector General Tarun Gauba, who investigated the Vyapam cases, while overall in-charge at Joint Director-level was V Murugesan.

Tarun Gauba was prematurely repatriated to the cadre recently as he wanted to attend a course abroad and his CBI term was coming to an end.

The fate of corruption case is crucial for the return of Rakesh Asthana, a Gujarat cadre IPS of 1984-batch who is heading Bureau of Civil Aviation Security and Narcotics Control Bureau, in the CBI where CVC clearance will be mandatory, sources said.

The case against him was registered on the basis of a complaint from Satish Sana, facing probe in the 2017 case allegedly involving meat exporter Moin Qureshi, alleging the officer had allegedly helped him to get a clean chit.

The CBI had also arrested Manoj Prasad, believed to be a middleman, when he returned from Dubai on October 16.

In July this year, M Nageswar Rao, who was trusted twice by the government to take the reins of the agency when it had removed Alok Verma and Rakesh Asthana, was suddenly transferred as Director General Fire Services, Civil Defence and Home Guard after curtailment of his tenure.

In May, the Delhi High Court had granted four more months to the CBI to complete investigation in the case against Rakesh Asthana, saying an incomplete probe can lead to termination of proceedings.

On January 11, the court had granted 10 weeks to the probe agency to complete the investigation. The CBI had approached the high court after completion of 10 weeks' time.

The agency had sought more time to complete its probe in the case so as to conduct the probe in a free, fair and transparent manner.

The CBI had said that it was necessary to give effect to the court's January 11 order and to conclude investigation in a proper manner and thus extension of time to conclude the investigation is required.

The plea for extension of time was opposed by the counsel for Mr Asthana, Mr Kumar and Mr Prasad.