Ring was an FBI informer. Three years later, Sanders was arrested with others who, posing as bounty hunters, killed two Valley residents. The fact that she routinely perjured herself came out when a corrupt agent cut a plea agreement. Most agencies have strict policies that prohibit fraternization with snitches and prohibit any crimes except those performed to further an investigation. In practice, rules quickly become gray.
Informers are capable liars and actors.
Many are bright and charismatic. They work with law officers who rely on them to bring down criminals. They worked for years as top informers until their handler, FBI agent John J. Connolly Jr., retired in 1990. Connolly was indicted in December for what prosecutors say was granting criminal carte blanche to Bulger and Flemmi. Last fall, U.S. District Judge Mark Wolfe's ruling condemned the FBI's overall informer policies and practices in the bureau's Boston office.