A Missouri man who stood trial five times before he was convicted of a 1991 murder became the first inmate to be executed amid the coronavirus pandemic on Tuesday evening. Walter Barton, 64, who was found guilty of the murder of Gladys Kuehler nearly three decades ago, was put to death by lethal injection despite several legal organizations calling for a re-examination of his case. His last words, issued in a statement before his execution, were: “I, Walter ‘Arkie’ Barton, am innocent and they are executing an innocent man!!”

The U.S. Supreme Court had rejected his application for a stay a few hours earlier, the Kansas City Star reports. Over the span of more than a decade, Barton stood trial five times for the killing of 81-year-old Gladys Kuehler, who was found dead in her Ozark home after having been stabbed more than 50 times and sexually assaulted. The American Bar Association and the Innocence Project were among the organizations to express concerns over Barton’s trial, and three of the 12 jurors reportedly expressed misgivings about the guilty verdict after learning of new crime scene analysis. “Walter Barton’s conviction relies solely upon two of the known leading causes of wrongful convictions—testimony from a jailhouse informant and flawed forensic science, in this case faulty blood pattern analysis,” Vanessa Potkin of the Innocence Project said in a statement Tuesday. The ACLU also condemned the execution, calling it a “dark and tragic reminder that Missouri’s criminal justice system is unabashedly flawed and rife with misplaced priorities.”