The killing of Yap's acting Attorney General is a tragedy and justice will prevail, the governor of the Micronesian state says.
Rachelle Bergeron was shot dead on Monday night by a single suspect outside her home after returning from a run with her dog.
The national and local government and the FBI are investigating the US citizen's killing, which has shocked the Yapese community.
Governor Henry Falan said it was a dark time for Yap.
"As governor of the state of Yap, I promise to do everything in my power to have justice prevail and restore civility into our society. This crime is under investigation."
Mr Falan said Rachelle Bergeron's husband was inside their home when she was shot.
Police earlier said a motive is unclear, with police investigations ongoing.
An online crowdfunding campaign for Ms Bergeron's funeral costs has raised more than $US15,000 so far.
The campaign organiser, Joe Adams, described her death as a "senseless and tragic act", and said the couple were "a few days away from their first wedding anniversary".
Ms Bergeron first arrived in Yap from the US in 2015, taking up the position of assistant Attorney General before being promoted to acting Attorney General in January.