Yet making a trafficking case remains difficult, in part because the women who were victims may not want to cooperate with the police. Only one has been talking to deputies, Sheriff Snyder said. He had lined up about a dozen Mandarin interpreters, but many other women refused to speak and were let go with an offer of assistance.

“I would never consider them prostitutes — it was really a rescue operation,” the sheriff said, training his anger at the men whose demand for sex kept the massage parlors in business. “The monsters are the men,” he added.

In addition to arresting men ranging in age from their 30s to at least one in his 80s, the police charged several women who appeared to be overseeing the operation with racketeering, money laundering and prostitution.

Sheriff Snyder said investigators, who worked with Immigration and Customs Enforcement, estimated the trafficking ring to be a $20 million international operation. Men paid between $100 and $200 for sex, the sheriff said; between $2 million and $3 million has been seized in Florida, he said, including a safe stuffed with Rolex watches.

State Attorney Dave Aronberg of Palm Beach County, whose office leads a human trafficking task force with the F.B.I., said trafficking foreigners to work in places like massage parlors can be more difficult to root out than trafficking, for example, American girls who are recruited in person or online.

“They come from countries where the police are part of the problem, and they’re smuggled into the country,” Mr. Aronberg said.