Los Angeles Police Department Sgt. Juan Terrazas said officers move deliberately through each spa if an undercover detective is offered a sexual act in exchange for money.
"In there, they go room-by-room," he said as detectives entered a Torrance spa.
Inside, an undercover officer said he found signs of prostitution.
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"We found multiple condoms inside," he said. "Some of the girls were wearing stilettos. That's not normal, common practice for massage therapists to be wearing. One was actually wearing a dress skirt, like a club skirt, and she tried to lock herself into a room."
One woman working at the spa was cited for solicitation of prostitution. Police say she agreed to sex with an undercover officer for $160.
"Once that is conveyed to our undercover officer, there's an exchange of monies, and when that occurs, then the violation has occurred," Terrazas said.
Detectives then moved to another parlor just east of Harbor City. After an undercover reported a transaction, several officers entered to speak with the women working inside and search for evidence. Police say two women from China were working there, and detectives believe they may not be working there fully by their choice.
"They both showed it -- classic symptoms of being either labor trafficked or human trafficked. Both of them. You can see it in their eyes," the undercover officer said. "They are victims."
Detectives say it's common to encounter trafficking victims in these types of businesses.
"So most of the time, they're back home, right? They're people from other countries. They're promised opportunity in America," said Terrazas. "And when they get down here, they have to pay that amount off. So they're forced into working these jobs to pay off the loan that they got to get into the U.S."
At the second spa, officers cited one woman for soliciting prostitution, and issued the business citations, including one for "no manager/supervisor on duty" and another one for evidence of "audio/video recording in massage rooms."
Police then wrapped up at a third parlor a few blocks away. An undercover officer wrote a citation after he said he was offered $40 for one sex act and $60 for another. Even as officers cite individual women, Terrazas said they also try to offer support.
"Our focus and our efforts are to save some of these girls. Some of these girls need some saving," he said.
ABC7 On Your Side Investigates repeatedly reached out to each of the three parlors cited during the operation. None returned requests for comment. Detectives say the two women they suspect are trafficking victims are no longer talking and are not cooperating with officers.