Kirstjen Michele Nielsen was born May 14, 1972, in Colorado Springs, Colorado. She earned a Bachelor of Science degree in foreign service from Georgetown University and a Juris Doctorate degree from the University of Virginia Law School.

After graduating from law school, Nielsen practiced corporate transactional law at Haynes and Boone LLP and worked for Senator Connie Mack of Florida. In 2004, President George W. Bush commissioned her as special assistant to the President for prevention. There she established and managed the Offices of Legislative Policy and Government Affairs at the newly formed Transportation Security Administration (TSA). Nielson also joined President Bush’s homeland security council to devise and execute response plans for domestic incidents.

In 2007, she became general counsel and president of the homeland security and private sector preparedness practice at Civitas Group LLC. Nielsen then founded and became president of Sunesis Consulting LLC, a private consulting firm focused on providing preparedness strategies.

Nielsen returned to government in January 2017 as chief of staff to John Kelly, who was secretary of the Department of Homeland Security. Nielsen’s main responsibility was to advise then-Secretary Kelly on operational, policy, and legal matters involving counter-terrorism, cybersecurity, and border security. When President Trump appointed Kelly as White House chief of staff in July 2017, Kelly brought Nielsen with him to become his deputy chief of staff.

President Trump nominated Nielsen as secretary of Homeland Security in October 2017. On December 5, 2017, the Senate confirmed Nielsen as 6th secretary of the department with a 62-37 vote. Nielsen was the first homeland security secretary who previously held a position within the department. Secretary Nielsen led the Trump administration’s focus to reduce immigration. Her tenure was controversial as she worked to implement Trump’s zero-tolerance family separation policy, taking children away from their parents at the border. The policy was so divisive that the Trump administration ended it after less than three months, but the administration requested two years to try to reunite children with their families due to inadequate record keeping.

Nielsen resigned as secretary on April 10, 2019, after President Trump became increasingly frustrated at the inability to curb immigration on the southern border of the country.