UPDATE: The U.S. Court of Appeals for the Eleventh Circuit stayed Madison's execution, ordering oral argument on his competency claim. Previously: Alabama is preparing to execute Vernon Madison (pictured) on May 12, as his lawyers continue to press their claim that the 65-year-old prisoner is incompetent to be executed. Defense lawyers say Madison, whom a trial judge sentenced to death despite the jury's recommendation of a life sentence, suffers from mental illness and has additional cognitive impairments, retrograde amnesia, and dementia as a result of strokes in May 2015 and January 2016. The strokes also have caused a significant drop in Madison's IQ, which now tests at 72, within the range the U.S. Supreme Court has recognized as supporting a diagnosis of intellectual disability. In addition, the strokes have left Madison legally blind. In its 1986 decision in Ford v. Wainwright, the Supreme Court ruled it unconstitutional for states to execute mentally incompetent prisoners, whom it defined as people who do not understand their punishment or why they are to be executed. Madison's lawyers have unsuccessfully argued in Alabama's state and federal courts that, because of his mental impairments, he is unable to understand why the state will execute him. An Alabama trial judge ruled earlier this month that Madison is competent, and the court denied his motion for a stay of execution. On May 6, he presented his competency claim to the federal district court, which denied relief on May 10. Madison's lawyers have appealed that ruling. Madison has been on death row for more than 30 years. His conviction for the murder of a white police officer has been overturned twice, once because prosecutors intentionally excluded black jurors from serving on the case and once because the prosecution presented improper testimony from an expert witness. Last week, the U.S. Supreme Court vacated a decision of the Alabama Court of Criminal Appeals upholding a death sentence imposed on Alabama death row prisoner Bart Johnson, and directed the state court to reconsider the constitutionality of Alabama's death-sentencing procedures. Madison's lawyers have sought review of his case in light of Johnson and are also seeking a stay of execution to permit him to litigate the constitutionality of the state's judicial override provisions.