Many LE agencies can perform such surveillance themselves; or get help from other local, county, state and federal resources if they lack the capability. Took less than 4 full days to covertly install and set up, obviously while the spa was closed and unattended. The warrant was easy to get based on compelling evidence presented by the LE detail.
"On Tuesday, January 15th, 2019, I obtained a search warrant for the authorization of the monitoring and recording of visual, non-audio conduct, for the target business. On Friday January 18th 2019, surveillance of the law enforcement video cameras began and was monitored for a period of five (5) days by members of the Jupiter Police Department's Operations Support Bureau."
The above is per hua-pc.pdf findable on the web. Anyone seriously interested should find and skim the 17 pages.