It doesn’t get worse than this for the nation’s premier investigating agency. On Thursday, the Supreme Court ordered the director of the Central Bureau of Investigation “not to interfere” in one of the agency’s most important inquiries. Ranjit Sinha might remain the head of the CBI for the moment – he’s due to retire on December 2 – but the apex court has expressed serious doubts about his ability to remain impartial in a crucial case. How did it come to this?

The Supreme Court chose not to specify why it was taking Sinha off the probe, except to say that it no longer trusted him. “To protect the faith in the institution and reputation of Director, CBI, we are not focusing on elaborate reasons,” the bench, headed by Chief Justice HL Dattu, said in its order. “We are not giving elaborate reasons as CBI has a reputation and it shall not be tarnished.”

What did the CBI director do?

Which is to say that there was enough material in the petition filed by the Centre for Public Interest Litigation that, if it made it to the public domain, would seriously damage Sinha’s reputation. To get a sense of what this material might be, all you have to do is look at CPIL’s petition.

The non-governmental organisation essentially told the apex court that a log of visitors to the CBI director’s house over the past year clearly indicated that questions could be raised about his role. In particular, top officials from the Reliance Anil Dhirubhai Ambani Group met Sinha at least 50 times over the last 15 months at his New Delhi residence.

Both the Reliance ADAG company itself, as well as three of its chief executives are currently on trial in the 2G spectrum scam case, where politicians and bureaucrats have been accused of giving away cheap spectrum in return for kickbacks. Moreover, Sinha has himself come under question for allegedly attempting to “save Reliance” in the case by reopening portions of the initial probe.

Who was the CBI director meeting?

In a story that was first broken by DNA and then later made its way to the court, it emerged that Ranjit Sinha, whose appointment as CBI director had itself come under question earlier, was meeting a number of people whom someone in his role might not want to be around.

Take meat exporter Moin Qureshi. This is the man who is currently under investigation by the Income Tax department for allegedly having illegal wealth. Qureshi has also been accused by Prime Minister Narendra Modi accused of having “close links” with the Congress leadership, and is alleged to be at the centre of a large hawala racket. The logs show that Qureshi met Sinha on at least 90 different occasions over the last 17 months.

Then there are Reliance ADAG officials Tony Jesudasan and AN Sethuraman. Jesudasan is considered the right-hand man of ADAG chief Anil Ambani, whereas Sethuraman is the company’s group president. Between the two of them, there were 50 meetings with Sinha over the last 17 months.

Vijay Darda, a Congress politician who is allegedly involved in the coal scam, and his son Devendra also met Sinha on 10 different occasions. And Mahendra Nahata, of Himachal Futuristic Communications Ltd, one of the alleged beneficiaries of the 2G scam through another company, visited Sinha’s house a whopping 71 times, according to the register.

What has come of those meetings?

It’s impossible to say exactly what effect these meetings could have had on Sinha’s conduct as CBI director, but one example might point in the appropriate direction. Earlier this year, news emerged that former Special Public Prosecutor in the 2G case UU Lalit, who is now a Supreme Court judge, had written a stern note to the CBI effectively claiming that Sinha had been trying to derail the case against Reliance ADAG.

The Deputy Inspector General in charge of the 2G case, Santosh Rastogi, had written a draft request to Lalit seeking a further probe against Reliance. The draft mentioned points that had been brought up by Sinha claiming there were new points which contradict the current chargesheet against the company. The implication of this request, however, was for the three-year-old case against Reliance to be suspended and opened afresh.

Lalit’s response was not kind. Insisting that the “CBI should never do this again,” he said following through on this matter would be tantamount to weakening the case and should not be done under any circumstances.

Sinha has also been accused of delaying the chargesheet in the Aircel-Maxis case, where former telecom minister Dayanidhi Maran is alleged to have abused his position in order to favour a telecom company.

The CBI director’s lawyer has disputed all these allegations, but the Supreme Court’s response to them was a little different: "It appears to us that all is not well.”