You do not have to say anything, the less you speak the better. Answer as short as possible and make sure you tell him you are late for an appointment, so they understand there could be "issues" if you are unjustly detained.
Answer questions politely and with 1 or 2 word answers.
May I ask you a couple questions? Briefly I am late for an appointment.
Were you in this
spa? Yes, but they took longer then expected and now I am late.
What did you do? massage
Do you know this
spa is ......? No
Have you ever.....? No
Have you seen/heard.....? No
Who did you see? I don't know