fbi has a field office in san juan puerto rico which covers the us virgin islands
https://www.justice.gov/usao-vi
https://www.justice.gov/usao-vi/about-district
https://www.fbi.gov/contact-us/field-offices/sanjuan/contacts/district-of-the-virgin-islands
who to call
https://www.justice.gov/usao-vi/citizen-complaints#humantraffic
Thanks!