Yep, for example, lots of cases with coerced confessions or just confessions obtained from individuals with developmental disabilities. The investigator would be the one who overdid it, not the prosecutor, who is often obliged to pursue the case if someone says they did the crime. Whether the confession is any good is up to the justice system. This applies to many semisciences or pseudoscience or expert witnesses or shoddy statistics. The prosecutor should look at the case in good faith [not tunnel vision] and rely on the courts to be fair arbiters. Then you have technical boondoggles like Bill Cosby where the prosecutors view the matters of law one way and eventually the appeals courts view it differently--whether he committed some crimes wasn't really the first order matter.