Missing necklace

We had a employee of A-Tech take photos of our ceiling in our bedroom for purposes of providing us with a quote for fixing a leak. I had in my wardrobe drawer a present for my daughter's birthday, a silver necklace. This was discovered to be missing after A-Tech left. I wrote to A-Tech and the owner responded by phone aggressively to me, denying that his employee had taken the necklace. He suggested that it was my domestic worker (who has worked for us without incident for 15 years). He suggested a lie detector test but I was not prepared to subject her to the indignity of such a test. I would not deal with this company again.