Washington (AP) — U.S. officials say Homeland Security Secretary Janet Napolitano is resigning to take a senior posting in the University of California system.

Napolitano told senior staff Friday she was leaving for California. Napolitano has led the department since the beginning of the Obama administration, just the third person to hold this post.

As head of Homeland Security, Napolitano oversee the United States Coast Guard.

The officials spoke on the condition of anonymity because her resignation had not been announced publicly.