How can I be charged for these offences when I never left the pet section and never touched or gave anyone a hard time?

I was in a store in the holding a three dollar bag of dog treats when I started looking for a coupon in my pocket. A clerk said that I was stealing the treats, I tried to explain but she would not listen saying I was trying to conceal the item in my pants. I needed to come with her. I sat the treats back on the shelf and left the store with her following me. A week later, the police called and said I was being accused of retail theft and disorderly conduct. I now have a court date. She said that I threw the treats at her which was not true. I always thought you had to pass the registers and leave the store to be accused. How did she know I did not intend to pay if she never gave me a chance to leave the pet section?