Unfortunately not every conviction can be vindicated through the technology of DNA evidence. Various falsely incarcerated persons suffer from injustices afflicted by bogus witnesses, unlawful police, court appointed defence attorneys, prosecutors and judges! One or more of the following factors typically contribute to a false conviction:
-Erroneous identification by the victim(s)/ witness(es)
-Fabrication of evidence by police or crime lab technicians
-Overzealous prosecutors who are concerned with winning instead of serving justice
-Court appointed defense attorneys are not always experienced in criminal law, let alone death penalty cases. It does happen that for instance divorce or bankruptcy attorneys have to defend clients who are accused of murder. Needless to say that it is too much for those lawyers, although they definetely do their best.
-Lack of proper police investigation
-False confessions that were physically or psychologically coerced
-Perjury by prosecution witnesses
-"Snitches"/ Informants/ Co-defendants being allowed to testify in court and making "deals" with the prosecutor
-Uncritical and untrained jurors. They are not aware of the "games" that are being played.
-Exclusion of other suspects
-Rulings of the judge who favors the prosecution
-Unethical news reporters who deliberately only tell half of the "story". They put pressure on the state to prosecute, convict and sometimes execute someone.
-Crucial evidence disappears, is destroyed or withheld from the defense
-Lack of resources prevents the defendant from hiring investigators and experts. However, thanks to the tax payers, the prosecutor has all the resources needed to win a conviction.
-Prejudice against a defendant's ethnity, race, religion, nationality, political or personal ideas
-Coerced plea bargains by the prosecutor's piling on of charges that would result in a much longer sentence or even the death penalty
The prosecutor's, law enforcement's and witnesses' immunity from suit allows them to get away with perjury and other felonies without being prosecuted and punished themselves