ROCKVILLE, Md. — A Montgomery County spa owner is under arrest and accused of operating her spa as a "house of prostitution."

Investigators say the owner Emily Zhang Lawrence had a long list of clients paying for illegal sex acts.

A customer of Rose's spa on Frederick Road was surprised to find the massage parlor closed and its owner arrested.

After a web tip, Montgomery County Police's Vice & Intelligence Unit started a four month investigation into the spa starting in February. Court documents outline how Lawrence was allegedly operating a "house of prostitution."

Investigators used a GPS tracking device on Lawrence and allege they traced her to a Germantown apartment where they say she was keeping six Chinese immigrants. 

They say she would pick the six women up and bring them to the spa, where the workers would allegedly perform illicit sex acts as employees of the spa and Lawrence would collect the money.

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Neighbors say they thought it was strange six women were all living in the same small apartment.

 "First of all, those rooms, there just a curtain, it's not like a closed room or something. If something going on you would have heard something," said a customer who asked not to be identified.

We went to Lawrence's Germantown townhouse and no one answered. Investigators say the women were recruited from Flushing, New York, known to them as a hub for human trafficking. 

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For months, investigators stopped 60 male customers exiting the spa -- 18 of them admitting they paid for a sex act inside the spa. The fallout has been large, the States Attorney's office in Montgomery County having to hand the case over to Frederick County, after it says a part-time contract employee at the Montgomery County States Attorney's office was involved in the case, creating a conflict of interest. The employee is no longer with the states attorney's office. 

Rose's Spa remains closed during the investigation.

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