Lyons' last day at ICE is May 31, Mullin said, Xinhua reported.
Earlier Thursday, Lyons testified before a House Appropriations subcommittee, where lawmakers questioned him about the unusually high number of deaths in ICE custody and the agency's plans to expand detention capacity going forward.
Lyons was named acting ICE director on March 9, 2025, by former DHS secretary Kristi Noem, who had demoted the previous acting director amid demands from US President Donald Trump to ramp up immigrant arrests and deportations.
ICE has been under immense scrutiny in recent months over issues that have drawn attention from lawmakers, oversight bodies and advocacy groups, including deaths in ICE detention facilities and aggressive immigration enforcement practices.
Democrats have called for reforms to ICE operations following the fatal shooting of two US citizens by federal agents in Minneapolis in January, but Republicans have rejected the demands, resulting in a lengthy deadlock in negotiations over DHS funding. The DHS has been shut down for two months.