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In January of 2015, Dennis Chassaniol and Andy Marty combined their 46 years of legal practice to create a new law firm. Dennis and Andy each brought extensive experience in civil and criminal trials to form Chassaniol & Marty, LLC. Dennis began his practice of law in 1995 as an assistant prosecutor in St. Charles County. As assistant prosecutor, Dennis brought to conclusion misdemeanors and felonies, through trial or plea deal, in the 11th Judicial Circuit.

From 1995 to 1998, Dennis worked at the St. Charles County Prosecutor’s Office before starting a private practice of law. Since then, Dennis has focused his practice on defending people charged with DWI, drug offenses, assault, traffic violations, driving while revoked, illegal use of firearms, and any misdemeanors or felonies in state or federal court. In addition to defending criminal cases, Dennis serves as the Municipal Judge in Lake Saint Louis, O’Fallon, Cottleville, Dardenne Prairie, and Winfield.

Andy began his legal career in 1987 as a research attorney at the Missouri Court of Appeals, Eastern District, for Judge William H. Crandall, Jr. In that position, Andy learned the details of appellate procedure and finer points of legal writing and analysis. After a short stint defending corporations in personal injury lawsuits, Andy changed his law practice to represent people critically injured against employers, corporations, and insurance companies.

Andy represents people injured at work, in car crashes and due to slips and falls on commercial property. Over the years, Andy has successfully recovered money through settlement or trial, in civil courts, and the Division of Workers’ Compensation, in both Missouri and Illinois, for lost wages, medical expenses, wrongful death, and permanent disability.

Shortly after Chassaniol & Marty, LLC was formed, Attorney Evan Bettag joined the firm. Evan graduated from St. Louis University School of Law in 2008. After graduating, Evan practiced law in Washington, D.C., assisting a large corporation to comply with government regulations before returning home to St. Charles County. At Chassaniol & Marty, Evan represents clients who are injured to receive just compensation for harms and losses in both Missouri and Illinois.

Workers Compensation

Car Accident

Personal Injury


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Chassaniol & Marty, LLC offers free consultations for personal injury, workers’ compensation, and criminal defense.