FREMONT — It was a nondescript home at the corner of Feliz Court and Portola Drive, in a residential neighborhood full of green lawns, gardens and one-story dwellings.

But Fremont police say this neighborhood held a lewd secret. One of the houses was secretly operating as a brothel.

It all started last November, when a tipster told police they’d observed strange men coming to the home at all hours of the day and night, staying about 15 minutes, then exiting. The police investigation that followed included surveillance and a ruse where investigators answered local prostitution ads and were directed to the home.

Police stopped one would-be customer who claimed he was going to the house for a massage, authorities said. Finally, in April, they raided the residence and reportedly found partitioned-off sections inside with lingerie, condoms, lotions and personal lubricant.

In late May, police identified 43-year-old Junlian Chen as a suspected operator of the brothel. Chen was arrested on suspicion of operating a house of ill fame, pimping and pandering, according to police records. Court records say Chen has not yet been charged.