A federal criminal complaint filed Oct. 25 in U.S. District Court outlines the undercover investigation into alien harboring and possible human trafficking in the South Bay.

The multi-agency investigation began in San Mateo after a neighbor called the police after suspicious activity in their neighborhood. Further investigation involved the San Jose Police Department, the northern district of California U.S. Attorney's Office, Immigrations and Customs Enforcement and the Internal Revenue Service.

The individuals who were arrested operated the 14 brothels, which on the surface were massage parlors, according to the complaint.

Federal and state agencies found 31 women at the various sites. Twenty-one women were from Taiwan; four were from Korea and three from China. The ages of the women ranged from 20 to 30 years old. No minors were involved.

The women are being interviewed as potential witnesses in the investigation.

U.S. Attorney Kevin Ryan said the agencies are still investigating whether the women were smuggled or trafficked into the country. The women who were brought to the United States illegally will be deported.