https://www.law.cornell.edu/wex/brady_rule
The Brady Rule, named after Brady v. Maryland, 373 U.S. 83 (1963), requires prosecutors to disclose materially exculpatory evidence in the government's possession to the defense. A "Brady material" or evidence the prosecutor is required to disclose under this rule includes any evidence favorable to the accused--evidence that goes towards negating a defendant's guilt, that would reduce a defendant's potential sentence, or evidence going to the credibility of a witness.
If the prosecution does not disclose material exculpatory evidence under this rule, and prejudice has ensued, the evidence will be suppressed. The evidence will be suppressed regardless of whether the prosecutor knew the evidence was in his or her possession, or whether or not the prosecutor intentionally or inadvertently withheld the evidence from the defense.
Further, in cases subsequent to Brady, the Supreme Court has eliminated the requirement for a defendant to have requested a favorable information, stating that the Prosecution has a constitutional duty to disclose, that is triggered by the potential impact of favorable but undisclosed evidence See Kyles v. Whitley 514 U.S. 419, 434 (1955); United States. v. Bagley, 473 U.S. 667 (1985).