A man was shot. Police found a gun inside the yard of a nearby home. A lab tested the gun and compared the grooves and scratches of its interior to the casings found at the crime scene. According to the examiner, the gun conclusively matched "to the exclusion of every other firearm in the world." End of story. Guilty verdict.
Government informants -or snitches as they are often referred to-are are nothing new to the criminal justice system.