Question

first thanks, i have a couple that live on a street that run parrell with ours,they are three lots over from ours. we moved in 17 yrs ago. maybe 10yrs ago my kids where playing in the back yard and found a green metal tractor. they when to the house behind our and ask them if it was their and they said no. so they pulled it out of the ive and washed it off.the chain was off and there was on front tires. so we put it in front of our house for looks.this spring we had a yard sale, it was going go until this couple showed up and in front of all the people buying from us,told us that we had stole it from them.we told them where we found it and they still said we stoled it.they left so we thought that was it! but sunday we where shopping and i was pushing my granddaughter having a good day and walked by a women with two teenagers.i was talking to my daughter on the phone. out loud she told them that i aws the men that stole the tractor. what can i do to stop this! thanks