Reversal for Brady error was required where criminal history of key prosecution witness was not disclosed. Price was convicted of being a felon in possession of a firearm based in large part on the testimony from a witness named Antoinette Phillips. The prosecutor did not disclose to Price that Phillips had lengthy history of criminal convictions and run-ins with the police that suggested she “had little regard for truth and honesty.” It was not clear whether the prosecutor himself ever possessed the information; but it was clear that his investigators did. The appellate court reversed the denial of Price’s new trial motion, holding that under longstanding due process principles, information in the possession of the prosecutor and his investigating officers that is helpful to the defendant, including evidence that might be used to impeach a government witness, must be disclosed to the defense prior to trial. A prosecutor may not evade this duty by remaining ignorant. Since the evidence of Phillips’s history was material, the prosecutor violated Price’s rights under Brady v. Maryland (1963) 373 U.S. 83.