Senator Jon Tester, a Montana Democrat, demanded that the Department of Homeland Security probe why Mateen was somehow able to clear a required background check in order to hold a security officer position with a federal contractor. Writing in late June to Department of Homeland Security Secretary Jeh Johnson, Tester pointed to "clear and troubling signs that Mateen's screening as an employee at G4S was inadequate." This was of particular concern to him given the company's work with DHS, that included a recent $234 million contract from DHS, involving Customs and Border Protection operations along the southern border as well as aiding U.S. Immigration and Customs Enforcement with immigrant transfers. G4S contracted previously with the military and national security, as well as the State, Justice and Energy Departments, and the Drug Enforcement Administration.