As America awaits the Mueller report, all eyes have turned to William Barr, the attorney general Donald Trump handpicked to navigate the conclusion of the Russian election-interference drama. Already Barr has enraged Democrats and placated Trump by deciding not to prosecute the president for obstruction of justice, and promising to redact many of the report’s juicier counter-intelligence details. Even more chilling were Barr’s comments last week on Capitol Hill, when he told lawmakers that he is assembling a team to investigate the origins of the Mueller report, during the summer of 2016, and that he believes “spying did occur” on the Trump campaign.

Veterans of the Justice Department are now expressing concerns that Barr—once viewed as the “institutionalist” the department needed—may be preparing to exact revenge against the president’s perceived enemies with politically motivated investigations. “What I find so disturbing is this statement by the attorney general, who, in the same breath, admits that he hasn’t carried out the investigation yet, but who characterizes it as criminal and inappropriate,” said Patrick Cotter, a former assistant U.S. attorney.

The issue isn’t that the D.O.J. shouldn’t conduct internal audits to ensure staff are complying with departmental policy, these sources say. Indeed, the Trump-Russia probe was “a very atypical, historical, large investigation,” said Cotter. But the attorney general’s word choice in discussing court-authorized surveillance raised a massive red flag. “Spying is a pejorative. Spying is a judgment. Spying is a condemnation,” Cotter continued. “It is an insult, and he shouldn’t have said it.”

The connotation of the word is such that sources I spoke with suggested Barr must have picked the word deliberately. “Anyone is human, and anyone can have a slip of the tongue,” said Elliot Williams, a former high-ranking D.O.J. official. But the distinction between lawfully authorized and illegal surveillance is “so fundamental to the job of attorney general, and so fundamental to anyone who has studied law enforcement or worked in law enforcement.” Spying, said Williams, “is such a radioactive term, and such a sensitive concept, that that was surprising, to say the least, to come from someone with his background.”

Cotter, too, considers the source. “This is not some guy on talk radio. This is the attorney general of the United States testifying before Congress. Everybody’s words matter, but his words matter a lot,” he told me.

Barr hedged somewhat, during the Senate hearing in which he dropped the S-bomb. “The question is whether it was predicated. Adequately predicated. And I’m not suggesting it wasn’t adequately predicated, but I need to explore that,” he told senators after asserting his belief that the Obama administration had spied on Trump. Still, the implications of his language could be explosive. According to Justice Department guidelines, predication for investigations, like the one the F.B.I. opened into the Trump campaign, is defined as “generally, allegations, reports, facts, or circumstances indicative of possible criminal or national-security-threatening activity, or the potential for acquiring information responsive to foreign-intelligence requirements—and supervisory approval must be obtained, to initiate predicated investigations. Corresponding to the stronger predication and approval requirements, all lawful methods may be used in predicated investigations.”

As former U.S. Attorney Harry Litman explained, this brings the focus directly back to the actions of former F.B.I. officials James Comey, Andrew McCabe, and even Lisa Page and Peter Strzok. “What he is saying is pretty ominous, because the people who would not have had an adequate predication would be the ones who started the counter-intelligence investigation,” he told me, adding that it boils down to “the whole ‘investigate the investigators’ mantra that Trump is so eager to sound.”