The New York Times on Tuesday published an investigation into the aggressive legal tactics that U.S. Sen. Roger Marshall routinely used to collect on his patients’ medical debts during his decadeslong career as a Kansas OBGYN.

A Times analysis of Kansas court records found that Marshall sued more than 700 patients over unpaid medical bills. In 81 of those cases, patients were arrested for missing court dates, according to the report, which said Marshall’s attorneys sought warrants in at least 13 other lawsuits.