- Rajeshwar Singh accuses Hasmukh Adhia of siding with "scamsters"
- Finance Ministry replies to letter, says allegation has malicious intent
- Over the years, Mr Singh has investigated many high-profile cases
Here are the 10 facts on this story:
In his letter to Finance Secretary Hasmukh Adhia earlier this month, Rajeshwar Singh accused him of siding with "scamsters" and compromising on national interest to settle scores. He also asked if he was being targeted because he spoke his mind and wasn't submissive.
Rajeshwar Singh's letter, dated 11 June, was leaked after the Supreme Court on Wednesday agreed that an officer who is "under a cloud" cannot investigate the sensitive Aircel-Maxis case.
In his letter, Mr Singh said he expected better from Mr Adhia and recalled the alleged harassment that he had faced in the past for investigating P Chidambaram in the Aircel-Maxis case when he was still the finance minister.
The Finance Ministry had responded to this letter, saying the allegations were based a figment of his imagination, written with a malicious intent, and amounted to wilful insubordination.
Rajeshwar Singh, who started his career as a police officer in Uttar Pradesh, had come to the centre on a deputation but was absorbed in the Enforcement Directorate, the investigative arm of the finance ministry that probes money laundering. The ED reports to Revenue Secretary Hasmukh Adhia.
Over the years, Mr Singh has investigated Madhu Koda scam, Jagan Reddy case, 2G scam and the Noida Ponzi scheme.
Rajeshwar Singh, who has a controversial track record, is seen to have led the Enforcement Directorate's crusade against P Chidambaram. This is also why the government's strong stance against him in the top court is surprising.
Sources suggest the ED officer, who felt the government was holding back his promotion as additional director, was reportedly investigated on orders of the finance ministry and PMO after allegations of corruption.
The government's senior law officer Vikramjit Banerjee, who handed over a report on the officer in sealed cover, also told the court on Wednesday that the government was willing to investigate the allegations against him. The court left it to the discretion of the government to take the call on this aspect.
One input sent by India's spy agency RAW that reportedly was made part of the centre's report to the court alleged that Rajeshwar Singh had come in touch with a Dubai-based person, Danish Shah who is also said to be working for Pakistan's ISI. The ED, however, contradicted this claim, pointing that Mr Singh had received just one call from a Dubai-based person in 2016 who had given important information regarding a case being investigated by the agency.