Kirstjen Nielsen's departure from the Department of Homeland Security means that 15 of President Trump's Cabinet-level appointments have departed, a number far higher than in previous administrations.
The deaths of two migrant children raise new questions about the quality of medical care at Border Patrol facilities. But pediatricians at the border have been raising these concerns for years.
Secretary Kirstjen Nielsen promises new "extraordinary protective measures" in the wake of the death of a second migrant child this month. They will require assistance from multiple federal agencies.