Thank you for the information and your question. I assume that these employees are "at will" employees and do not have a contract that limits your ability to terminate them. If so, then as the employer, you can terminate them for any, or no, reason and with no notice or warning. The only exception, other than a contractual restriction, is that an employer cannot target a particular employee for termination simply because of their race, national origin, gender, age (over 40), disability, pregnancy or military service.
Anyone can sue whether they have a case or not, so I can't predict what they will do, but unless their situation fits into one of the exceptions I mentioned, you could lawfully let them go. You may have issues if you choose to dispute their eligibility for unemployment benefits, which is a different legal issue, as you will have to carry the burden of proof that they were involved in the theft. But again, that doesn't mean you can't terminate them, just that they might win their unemployment cases.
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