Kirstjen Nielsen is an American attorney and national security expert who was born on May 14, 1972, in Colorado Springs, Colorado, in the United States. She was born to Phyllis Michele Nielsen and James McHenry Nielsen who both served as physicians in the United States Army. She grew up as the oldest of three siblings and relocated with her family to Clearwater, Florida. Neilsen attended the Georgetown School of Foreign Service where she graduated with a Bachelor of Science degree. She went on to attend the University of Virginia School of Law where she received her Juris Doctorate in 1999. Nielsen also studied Janapnse at Nanzan University n Nagoya, Japan. Nielsen was Special Assistant to George W. Bush and acted as Director for Prevention, Preparedness, and Response at the White House Homeland Security Council.

She left the Bush administration in 2008 and founded Sunesis Consulting where she was awarded a $450,000 government contract. She also served as John F. Kelly's chief of staff at the United States Department of Homeland Security. Nielsen once again began working for a President in 2017 when she joined the Trump administration and became the United States Secretary of Homeland Security in 2017 and is still acting in that position today.