A top immigration policy expert accused a right-wing online news source of spreading an “outrageous lie” on Monday about the US Department of Homeland Security’s top statistician, who resigned over the weekend and cited President Donald Trump’s “war on immigrants” as a major reason for his departure.America First Post wrote in a post on social media that Marc Rosenblum, who until recently was the executive director of the DHS Office of Homeland Security Statistics (OHSS), “easily could’ve been underreporting deportations or illegal populations, ruining data.”Aaron Reichlin-Melnick, senior fellow at the American Immigration Council, countered that Rosenblum sought under both the first Trump administration and the Biden administration to publish “the most transparent data on immigration enforcement ever; monthly information on [US Immigration and Customs Enforcement and Customs and Border Protection] arrests and removals, stuff that had NEVER been published before.”Such data has not been published since the first days of Trump’s second term in the White House, said Reichlin-Melnick, as the president has ramped up deportation operations and federal agents have violently carried out his anti-immigration agenda—arresting more than 10,000 people in a recent five-day span and killing at least 11 people during enforcement operations.In a post on LinkedIn, Rosenblum wrote that over 10 years, the team he managed at OHSS grew from 11 people to 45 people under the Biden administration.“We matured official data processing to update monthly,” wrote Rosenblum. “We launched new lines of daily and weekly internal reports. We massively expanded our analytic capacity.”“My OHSS co-workers are outstanding career federal civil servants. They are smart, mission-focused experts who produce high-quality results in a challenging and often hostile work environment,” he continued. “But it will come as no surprise that I’m thrilled to end my relationship with the current administration. Between the war on immigrants, the war on feds, and the war on facts (not to mention the crazy war in Iran and the brazen corruption), I just need a change.”Daniel Delgado, a former DHS deputy assistant secretary for immigration policy, said the department was “far better off for the work that Marc accomplished, no matter how hard the current incompetent leadership try to hide it.”David Bier, director of immigration studies at the libertarian Cato Institute—which has found that the majority of immigration arrests made last year were of people who had no criminal convictions—told NOTUS last November that under the Trump administration, DHS was providing “no accountability, no way to assess, no public understanding about what’s really going on that is not curated by a press release from the agency.”Reichlin-Melnick has also frequently spoken out about the lack of data being publicly released by DHS to back up its claims about immigration arrests.While DHS has repeatedly claimed in public statements that its agents are getting “the worst of the worst off our streets,” the agency’s own “Worst of the Worst” database released late last year showed less than 10,000 people who had been arrested—a tiny fraction of the 220,000 people who had been detained by federal agents up to that point.“Marc Rosenblum was one of the most dedicated civil servants I’ve ever met, a man who spent his career working to get DHS to share more data,” said Reichlin-Melnick. “Since Trump took office last year, his office has been repeatedly blocked from sharing previously public data.”