IN HIS fourteen seasons on “The Apprentice”, a television show testing contestants’ business acumen and mettle, Donald Trump developed a signature line for dismissing hapless aspirants. Every time he let somebody go with his trademark "you're fired!", Mr Trump offered at least a few words of critique. “I just don’t want somebody running one of my companies that’s going to be beaten up so badly”, he told one contestant. “You’ve been lazy”, he barked at another, “you’ve been nothing but trouble”.

But on March 11th, when Mr Trump requested resignation letters from 46 US attorneys, he offered no explanation for dumping Preet Bharara, a seven-year veteran of the southern district of New York. It is hardly unusual for presidents to replace US attorneys, lawyers tasked with ensuring “that the laws be faithfully executed” in the 94 federal districts they oversee. A change of party in the White House typically inspires federal prosecutors to issue letters of resignation. In 1993, Bill Clinton fired them all in one day.

But Mr Bharara was a unique case: the Indian-born prosecutor known for his toughness and for remaining untethered to politics or party had been assured by the president-elect that he could keep his job. After a meeting in Trump Tower in late November, Mr Bharara said Mr Trump had asked him “whether or not I’d be prepared to stay on as the United States attorney to do the work as we have done it, independently, without fear or favour for the last seven years”. Mr Bharara’s answer was yes: “I said I would absolutely consider staying on. I agreed to stay on.” The president-elect’s request was echoed, he said, by the man who would soon be his new boss: Jeff Sessions, the incoming attorney-general and head of the Justice department.

When Mr Trump demanded Mr Bharara’s resignation three months later, without indicating why he had undergone a change of heart, the jilted prosecutor did not go quietly. Mr Bharara refused the order to tender his resignation, and a few hours later Mr Trump stepped back into his familiar role as firer-in-chief. “I did not resign”, Mr Bharara wrote on Twitter. “Moments ago I was fired.” Serving as US attorney in New York, he said, “will forever be the greatest honour of my professional life”. Why did Mr Trump renege on his promise to Mr Bharara? There seem to be three possibilities, none of them offering encouraging signs about the Trump administration.

One reason for the abrupt about-face may have been Mr Trump’s favourite source of political edification: Fox News. On March 9th, Fox’s Sean Hannity said holdover lawyers from the Obama era may be “saboteurs” who are leaking damaging information about the administration. He encouraged Mr Trump to clear US attorneys’ offices of Obama appointees who had not already offered their resignations. Two days later, Mr Trump did just that. Spokespersons for the administration insist the plea from Mr Hannity—whose network happened to be under investigation by Mr Bharara for sexual harassment allegations—played no role in inspiring the president’s act; one source told Politico’s Josh Dawsey that the purge had been in the works “for a while”.

Whether or not Mr Hannity’s appeal caught Mr Trump’s eye, Mr Bharara’s reputation as an equal-opportunity prosecutor—sniffing out corruption and pursuing it no matter where it may be or who might be engaging in it—may have begun to worry the new president. Just days after beginning his position in 2009, Mr Bharara did not flinch when presented with evidence that a donor to Senator Chuck Schumer—his former boss and recommender—may have been engaged in bank fraud. The 41-year-old attorney went forward with the investigation. Mr Bharara’s office later successfully prosecuted cases involving Wall Street, organised crime, civil rights and terrorism—as well as high-profile corruption cases against Republican and Democratic politicians. Mr Trump may have reconsidered leaving such a dogged US attorney in place who pays no homage to party. In the event of potential legal trouble, he may have judged it wise to have a friendly, loyal appointee in place.

Or Mr Trump’s concern may have been a good deal more specific and immediate. In a cryptic statement seemingly crafted to provoke speculation and raise questions about the man who fired him, Mr Bharara tweeted this on March 12: “By the way, now I know what the Moreland Commission must have felt like.” The reference was lost on no one who has watched New York state politics over the past several years. In 2014, New York’s Democratic governor, Andrew Cuomo, disbanded the Moreland Commission, the very ethics watchdog he had set up nine months earlier and which had begun investigating Democratic Party fundraising lapses. Mr Cuomo’s move provoked wide consternation and an investigation from Mr Bharara’s office, though no charges were filed.

For Mr Bharara to analogise his own firing to the dismantling of the Moreland Commission is to hint that he may have begun an investigation into activity of interest to the president—perhaps even of something the president himself may have done. A congressman from Michigan, John Conyers, said Mr Bharara’s tweet could be a sign he had been looking into “a range of potential improper activity emanating from Trump Tower and the Trump campaign, as well as entities with financial ties to the president or the Trump organisation”. The puzzling firing, in other words, may have been designed to cut an inquiry by Mr Bharara off at the pass.