It seems to be what gets thrown in as the assumed culprit more often than not when a young woman goes missing or ends up dead under suspicious circumstances. I see it frequently when reading speculation on murder/abduction cases elsewhere. That's not to say that human trafficking isn't a huge problem, it just seems to currently be a popular theory that people jump to, no matter the facts or context of each individual case. It reminds me of the 'Satanic Panic' ritual abuse paranoia that was prevalent in the 80s. JMO, of course.
With LE saying they believe there is no threat to the public, it would seem to indicate they know the incident is an isolated one. Perhaps they have enough info to know who is involved, but need to investigate further whether there was any criminal misconduct surrounding the death.