The man picked by Donald Trump to be the next Homeland Security secretary does not appear to know what Homeland Security Investigations (HSI) does.
Oklahoma Sen. Markwayne Mullin, 48, seemed confused at his Senate Homeland Security and Governmental Affairs Committee confirmation hearing on Wednesday when Sen. Ruben Gallego, 46, asked him a simple question about one of the Department of Homeland Security’s (DHS) most important law-enforcement components.
“What is the primary mission of Homeland Security Investigations?” Gallego asked. Mullin—the only senator without at least a bachelor’s degree—failed to give a direct answer.
Instead, he drifted into a broad response about DHS’s many agencies all working toward one common goal.
Gallego then stepped in and filled the gap himself, noting that HSI is the unit that tackles things like human trafficking, human smuggling, counterfeit goods, and bank fraud.
Mullin’s answer will likely leave his potential future underlings a bit concerned. HSI is not an obscure agency buried deep in the department—it is ICE’s criminal-investigations arm.
Its core mission, according to ICE, is protecting the homeland from transnational crime and other threats. Its agents investigate the illegal movement of people, goods, money, contraband, weapons, and sensitive technology.
It reaches into trafficking, smuggling, exploitation, cybercrime, fraud, and other cross-border criminal networks, with a remit much wider than removal work handled by ICE’s enforcement side.
Mullin’s lack of knowledge exposed a deeper problem, coming as it did amid President Trump’s mass deportation push.
HSI is supposed to handle some of the ugliest and most complex cases in the federal system. But its specialized agents have already been dragged so far into immigration operations that the distinction between criminal investigations and removal work has been badly blurred.
As the Daily Beast reported in November, citing a New York Times report that leaned on documents and interviews with more than 65 current and former officials, thousands have been reassigned away from areas that are not immigration-related.
The Times found HSI spent about 33 percent fewer hours on child-exploitation cases from February to April 2025. In Los Angeles, a five-agent child-exploitation squad was put on immigration duty, leaving agents trying to keep cases alive on nights and weekends. The same report said work tied to sex trafficking, terrorism, and illicit finance had also been slowed.
The HSI flub was not Mullin’s only problem, however. A bigger political headache may be the mystery overseas trip he has been hinting at for days and refusing to explain in public.
Mullin had earlier been pressed over past suggestions that he had “smelled war” despite never serving in the military. At the hearing, he acknowledged taking what he called an “official” and “classified” trip in 2016 after being asked in 2015 to train with a “very small contingency.” He would not disclose the location or the mission.
That issue is now being driven in part by committee chair Sen. Rand Paul, 63, who was already furious with Mullin over past comments about a 2017 assault that left Paul with broken ribs.
After the hearing, Paul said lawmakers had agreed to head to a secure room to hear more about the classified mission. He said the story “may be innocent,” but added that it naturally makes people curious when a nominee talks about doing a secret mission and will not say for whom.
Paul also said he still plans to vote no on Mullin’s confirmation. Because the committee has eight Republicans and seven Democrats, that could force Mullin to find at least one Democratic vote to move forward.
The Daily Beast has contacted the Department of Homeland Security and the White House for comment.
