FBI joined the investigation of the death of 33-year-old Rachelle Bergeron who was shot dead on 14 October outside her house in the Micronesian state of Yap.
Rachelle was a US-trained lawyer who specialised in fighting human trafficking, and was acting attorney general on Yap.
She had been working in the Federated States of Micronesia since 2015, and was due to stay for four years.
Rachelle was killed while returning home from waking her dog, her dog also died.
She was staying in Yap along with her German husband who is a pilot but worked for a Christian missionary group.
Her mother, while speaking with the newspapers said she was planning to adopt a local girl who she found sleeping outside their house, with the family due to move back to the US on Christmas Day.
She had previously worked in India, focusing on the trafficking of women and children, before she went to Micronesia.
After her murder, officials called investigators from the United States FBI to help with the investigation.
Arrests were made and now the case was proceeding towards the courts where the final stage of conviction is expected. Authorities have not revealed names of the suspects.
Micronesia consists of some 600 islands grouped into the four states of Yap, Kosrae, Pohnpei and Chuuk. Occupying a very small land mass, the remote islands are scattered over an ocean expanse in the western Pacific five times the size of France. With a population of only 12,000 and low rates of violent crime.