Defamation/Cease and Desist

Hi, I have a question pertaining to defamation and if we have any legal options to make it stop. I live in a small town of around 4,000 people. My family owns a small local business. My father also serves on the town's city council and has done so for nearly 30 years. Over the past year a man, angry with the city, has created a Facebook group now with over 700 people that he uses to defame the city and make false claims. He attacks the mayor, city clerk, city council, fire chief, even the city attorney, and other city officials as being corrupt and breaking the law. All of this culminating in this angry (unemployed) man making an unsuccessful run for mayor this past election. It has been clear to me for a long time that all along his goal was to make a "stink" in hopes of drumming up enough votes to get elected to office so he can have a job and get a nice paycheck. Regardless of his motives this brings me to my problem. My father has been a life long servant in this community and goes far beyond what any one person should do to try and help make it a better place to live. Being the good man my father is he was the first person to go to this man when he first started showing up at council meetings claiming of crimes being committed. My father went to him and listened to him talk for several hours to try and get to the bottom of things and if there is wrong doing then take appropriate action. However, this angry man for some reason has now been targeting my father with horrible lies that he is stealing from the city and misappropriating funds as well as covering up crimes by other city officials. All of these are ludicrous lies of a bitter little man and we have ignored them for many months now. Unfortunately, the man has grown a large audience with his Facebook group and has undoubtedly made some of them believe his lies. This has harmed my fathers good name and in turn has damaged our business causing us to lose customers. Our family is suffering because of one mans lies and slander. I am trying to find out if we have any legal recourse in this matter? I am not looking to sue for damages because the man couldn't pay even if he was prosecuted. I simply want the man to stop making up lies and causing undue stress to my father, my mother, and his business. Can you sue to have this removed? Can an attorney send a cease and desist notice? I know freedom of speech makes it virtually impossible to do anything but surely there is some action that can be taken. How can one petty man be able to destroy good hard working people's reputations without any recourse? Thank you for taking the time to read and comment.

Defamation/Cease and Desist