The Department of Homeland Security is a part of the Executive Branch of the United States government. Its purpose is to evaluate and neutralize threats to national security. Agencies under the Department of Homeland Security include Secret Service and Coast Guard.
Ralph Burton, a private investigator hired by Kate Warner, reported to Homeland Security that Reza Naiyeer was possibly involved with Syed Ali and the Second Wave terrorist cell. They alerted CTU and Tony Almeida investigated his background ("Day 2: 10:00am-11:00am").
Shortly after the President found out about the theft of Sentox nerve gas from the Ontario Airport, Chief of Staff Walt Cummings went to meet with the Homeland Security teams to prepare evacuation scenarios.("Day 5: 11:00am-12:00pm")
The department played a pivotal role in Day 5 when DHS employee Karen Hayes and her associate Miles Papazian took over CTU Los Angeles following a Sentox VX nerve gas attack that killed nearly 40% of the staff. The takeover was ordered by Vice President Hal Gardner and involved bringing in many people from DHS, including Jim Hill, to absorb CTU into DHS's existing structure and protocols. Hayes and Papazian were able to assert control over CTU throughout the day as a result of their newfound authority from the White House and the surge in new CTU employees that came from DHS.
Via a bulletin issued by White House Chief of Staff Tom Lennox, Homeland Security was to flag any Government employees with a Muslim background and have their duties restricted. This included CTU Agent Nadia Yassir, who brought her complaint to Bill Buchanan.
- Head of Department, Day 3: Joseph O'Laughlin (David Palmer Administration)
- Head of Department, Day 5: Karen Hayes (Charles Logan Administration)
- Head of Department, Day 7: Tim Woods (Allison Taylor Administration)
- Miles Papazian
- Valerie Harris
- Jim Hill
- Ed's assistant
- Data analyst