I did see on CNN a story about two persons that were wrongfully convicted on bad evidence from a laboratory that is organized within the state's justice department. Basically, the lab works for the prosecution. According to that report, 11 states operate that way (not Nevada). The report uncovered vile corruption that did a huge injustice to two persons.
Here is some of that story:
As shocking as the buried evidence was a statement made by the SBI analyst, Duane Deaver, on the stand. When asked why he didn't report the key test, Deaver said he was just complying with the lab's accepted practices of the time. (Since then, Deaver has been fired by the SBI, his lawyer says.)