Yes, but it should have been reported to police as a theft, so you have proof 

Thank you - yes it was reported to the police  and investigated by federal authorities.  Unfortunately there was no insurance.

I'm not sure about Schedule C.  Casualty loss usually goes on Form 4684, then Form 4797 (or at least on the 1040 line for that).  It makes a difference, of course, in SE tax.  If Schedule C is the wrong place, and it makes a $5,000 tax difference, who pays the Section 6662 penalty?