Police have arrested a Tyngsborough spa manager in connection with running a brothel following a months-long investigation, Tyngsborough police announced Wednesday. Lancaster resident Chun Xiang Cao, 60, has been charged with keeping a house of prostitution, maintaining a house of prostitution and sexual conduct for a fee, Tyngsborough police said in a press release. She is the manager of Healthy Wellness Spa on Middlesex Road in Tyngsborough. Over the next few months, Tyngsborough police and Massachusetts State Police troopers surveilled Healthy Wellness Spa. Tyngsborough police ask that anyone with information regarding the investigation into Healthy Wellness Spa or Cao call the department at 978-649-7504.