If you are truly interested, you might search the Internet.
Here's a brief synopsis from
http://www.deathpenaltyinfo.org/arti...scid=6&did=141
"Prosecutorial or police misconduct played a part in 63% of the convictions that DNA testing by the Innocence Project later overturned. Since 1963, at least 381 murder convictions in the United States have been reversed because of misconduct by police or prosecutors."