You can claim this as a Casualty and Theft loss, but the IRS wants you to prove that a theft occurred. Here's what they say:
Theft loss proof:
For a theft loss, you should be able to show all of the following.
When you discovered that your property was missing.
That your property was stolen.
That you were the owner of the property.
Whether a claim for reimbursement exists for which there is a reasonable expectation of recovery.
https://www.irs.gov/pub/irs-pdf/p547.pdf
You can see that if you filed a police report that would be very helpful for your case, in case the IRS audits your return..
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
