Slander victim

[youllfindtheway]

I got an email from a boutique saying they are missing an item and they believe I have it due to witnesses and video tape. What should I do? Should I ask to see the video even though there were no camera there lol

Thanks

Ps and I just know that the "witness" was telling everyone there at the boutique including other customers. How serious it would be if I sue this person and the store?