My dad beats my dog because he thinks he got into the garden and destroyed the tomatoes and the flowers. Help?

Ok, now I was really angry ! My dad just started beating my dog because he thought the dog destroyed the tomatoes and the flowers in the garden. He has no evidence that my dog did it , but still he doesn't want to listen to me. I saw cat footprints on the ground... The dog did't wen't there to do it's... thing... (let's not say a bad word) because there were no dog excrements. What can I do to proove my dad that he was wrong ?