The acting head of the Drug Enforcement Agency suddenly resigned Tuesday, citing his responsibility to “keep the public trust” and to “act honorably,” The New York Times reports, the latest in a steady stream of top U.S. officials to leave the administration, either voluntarily or otherwise. Law enforcement officials told the paper that Chuck Rosenberg, an Obama appointee who previously served as chief of staff to former F.B.I. director James Comey, “had become convinced that President Trump had little respect for the law.”

Although he gave no specific reason for his departure in a message to D.E.A. staffers, Rosenberg’s resignation comes weeks after he publicly rebuked Donald Trump for a speech at the end of July that appeared to encourage police brutality against suspected criminals. “When you guys put somebody in the car and you’re protecting their head, you know, the way you put the hand over?” Trump had said before a crowd of law enforcement officers in Long Island, telling them not to worry about being “too nice” when conducting arrests. “Like, don’t hit their head, and they just killed somebody—don’t hit their head, I said, ‘You can take the hand away, O.K.?’”

In an agency-wide memo, Rosenberg said those comments “condoned police misconduct” and said the D.E.A. holds itself to a higher standard. “In writing to you, I seek to advance no political, partisan, or personal agenda. Nor do I believe that a Special Agent or Task Force Officer of the D.E.A. would mistreat a defendant. I know you would not,” he wrote at the time. “I write because we have an obligation to speak out when something is wrong. That’s what law enforcement officers do. That’s what you do. We fix stuff. At least, we try.”

Politico reported that Rosenberg had considered resigning at the time, despite overtures from Deputy Attorney General Rod Rosenstein to see if he would consider being nominated to head the D.E.A. permanently, or moved to another agency. Rosenberg allegedly declined.

“The neighborhoods in which we live are better for your commitment to the rule of law, dedication to the cause of justice and perseverance in the face of adversity,” Rosenberg said in his message to employees Tuesday. “I will continue to root for you, now from the sidelines.”

With Rosenberg’s departure, the D.E.A. may now take a more Trumpian turn. While the Drug Enforcement Agency is a critical tool in the federal government’s war on crime, Rosenberg didn’t always see eye to eye with other members of the administration. Rosenberg and Attorney General Jeff Sessions had reportedly been at loggerheads over whether to prioritize the fight against MS-13, a Central American gang often invoked by Trump, or against the more well-financed and well-organized drug cartels. With a new appointee, Trump and Sessions—an unapologetic believer in the now unfashionable War on Drugs—are likely to install a more vocal culture warrior.

The Washington Post reported that Col. Joseph R. Fuentes, the head of the New Jersey State Police, was a likely candidate to replace Rosenberg. A staunch Obama critic who had criticized his decision to reopen diplomatic relations with Cuba, Fuentes, a Trump supporter, hailed “a renewed sense of optimism and moral superiority that justice will prevail,’’ upon the president’s inauguration in January.