On March 30, 1867, the United States reached an agreement to purchase Alaska from Russia for a price of $7.2 million. The Treaty with Russia was negotiated and signed by Secretary of State William Seward and Russian Minister to the United States Edouard de Stoeckl.
The Senate approved the treaty of purchase on April 9; President Andrew Johnson signed the treaty on May 28, and Alaska was formally transferred to the United States on October 18, 1867. This purchase ended Russia's presence in North America and ensured U.S. access to the Pacific northern rim.
It isn't quite specified who administered Alaska first. Sorry if this isn't the answer you were looking for.