It's not okay. But until there's a radical change of culture for prosecutors, the innocent will continue to be at risk. According to Pace University law professor and former Manhattan assistant district attorney Bennett Gershman, who wrote the book Prosecutorial Misconduct, prosecutors are a significant part of the reason innocent people are sent to prison and death row. Once they have a suspect, they don't look any further. They don't consider contradictory evidence, because they already have their suspect.
Society is no safer when the innocent are convicted.
Not only do we destroy the life of the person put behind bars, but the real criminal is still walking around. To avoid this, prosecutors are required to share with the defense any exculpatory evidence or information that may militate against the defendant's guilt, such as contradictory witness statements or the names of other suspects. But in a distressing number of instances the evidence is simply not turned over. In 20 percent of those cases it was due to prosecutors withholding exculpatory evidence. The paper also found that few federal prosecutors are ever brought to account for this type of misconduct.