A New York prosecutor in the high-profile murder trial of an 11-year-old boy has revealed that a witness saw someone who was not the accused entering the boy's home minutes before he was murdered. On trial for the murder is the boyfriend of the boy's mother despite no forensic evidence tying him to the case. The man allegedly seen entering the house was an ex-boyfriend of the mother.
Prosecutors are required to reveal any evidence they uncover that may be favorable to the defense. This has been the law since the 1963 Brady v. Maryland U.S. Supreme Court decision. If it is discovered after the fact that the evidence was not revealed, it could lead to a retrial. Unfortunately, prosecutors still do not always adhere to this requirement. However, if they fail to do so and it is discovered, it could result in a mistrial.
In another case, a man was convicted of robbery. Although the person who committed the robbery was described with dreadlocks, a photo of the man discovered by another prosecutor two days before the trial showed a short-haired man. The man got a new trial despite the prosecutor's argument that he could have worn a wig. At issue was not proof of the man's innocence but the fact that the photo was important for his defense.
There are several ways in which prosecutors or police might hide evidence or obtain evidence in a way that is not legal, and when people believe their rights have been violated, including the belief that the prosecution has favorable evidence they are not revealing, they may want to discuss this with their attorney as part of their criminal defense strategy.