Money’s missing from the till–what are our discipline options?

Q: “On several occasions at our medical center, when we collect the envelopes in the morning with the cash from the night before, some cash is missing. At the end of the shift, the registrar places the cash in a locked safe. Can we deduct the missing amount from the paycheck of the registrar who was responsible to collect the cash and store it in the locked safe?” – Mendel, New York