My heart breaks for you.
As others have stated in this thread it is an all to common occurrence in nursing facilities. In our experience an afghan disappeared never to be seen again. The staff in my observation had a high turnover rate during our Mother's 1 year stay. Under paid, under staffed, under appreciated, this not by any means is an excuse for theft, nor to say that it is staff.
Unfortunately in the U.S. unless you are extremely wealthy and are self-insured, the care of the elderly is alarming with cursory oversight to protect and care for fragile end of life care.