U.S. Immigration and Customs Enforcement Director Todd Lyons resigned Thursday, submitting his letter to the Department of Homeland Security just hours after appearing before the House Appropriations Subcommittee on Homeland Security to discuss the agency’s budget.

During that hearing, Lyons revealed that ICE’s Homeland Security Investigations division had uncovered what he described as the largest gift card fraud operation on record. He alleged the scheme involved Chinese nationals in the U.S. illegally and tied the activity to transnational groups connected to the Chinese Communist Party. According to a post from the White House Rapid Response 47 team’s social media account, Lyons said the proceeds were funneled back to military units in China.

In his testimony, he stated: “HSI actually broke the largest gift card fraud case ever, and it was from transnational gangs within the CCP that were sending that money back to military units in China…and it was unfortunately military age Chinese males that entered under the last administration.”

Lyons’ resignation came shortly after those remarks. In a letter obtained by The New York Times, he cited personal reasons for stepping down, calling his tenure leading the agency he served for two decades a “tremendous honor.”

“My sons are both reaching a pivotal point in their lives, and my wife and I wish to spend as much time as possible with them,” Lyons wrote in his resignation letter. “This was not an easy decision, but I believe it is the right one for me and my family at this time.”

Homeland Security Secretary Markwayne Mullin responded by praising Lyons, describing him as a “great leader of ICE and a key player in helping the Trump administration remove murderers, rapists, pedophiles, terrorists, and gang members from American communities.”

White House deputy chief of staff Stephen Miller also weighed in, saying, “Todd is a phenomenal patriot and dedicated leader who has been at the center of President Trump’s historic efforts to secure our homeland and reverse the Democrats’ sinister border invasion.”