WEBSTER, Mass. — A massage spa in Webster has been ordered to close their doors following a months-long investigation into illegal activity happening within the establishment, police say.

The Webster Police Department said there’s an ongoing investigation into Webster Asian Bodywork, where men were allegedly receiving sexual services for a fee. Webster police are calling this a complex case because of the victims involved and the process of gathering information.

“These are very difficult because it's because of the acts that are being performed," Chief Michael Shaw said. "It's not like you can send an undercover officer in there to do to do that. So, there's a lot of surveillance. There's a lot of other investigatory techniques that have to be done.”

Shaw said Webster detectives, along with FBI agents and South Worcester County detectives, served a search warrant to 269 Main St. on Nov. 15.

Detectives received and corroborated information of sex acts being done in within the business. On Dec. 2, the Board of Health issued a cease-and-desist order to Webster Asian Bodywork.

According to the social media post, one employee was found to be living within the commercial space. While the investigation is ongoing, Shaw said it’s complex because of the nature of the criminal acts.

“A lot of these businesses have ties to human trafficking. So, I know a lot of people are probably going to wonder, well, ‘how come no arrests were made?’ You know, a lot of the times that the employees of these businesses are, in fact, victims themselves, a lot of them are immigrants from other countries, normally China," Shaw said. "And a lot of these businesses are tied to an organized crime syndicate that is out-of-state. It's international. It's very, very difficult to prosecute.”

Shaw said his department is looking into establishing guidelines for starting a massage spa in the Webster to further hinder similar illegal activity from coming up. And they’re hoping this investigation leads to larger findings to go after any possible source of human trafficking.