The problem of racial bias among police [has] been a concern of the FBI for at least a decade. 10 years ago ... the FBI warned of the potential consequences - including bias - of white supremacist groups infiltrating local and state law enforcement, indicating it was a significant threat to national security. In the 2006 bulletin, the FBI detailed the threat of white nationalists and skinheads infiltrating police in order to disrupt investigations against fellow members and recruit other supremacists. The bulletin was released during a period of scandal for many law enforcement agencies throughout the country, including a neo-Nazi gang formed by members of the Los Angeles County Sheriff's Department. Similar investigations revealed officers and entire agencies with hate group ties in Illinois, Ohio and Texas. Much of the bulletin has been redacted, but in it, the FBI ... warned of "ghost skins," hate group members who don't overtly display their beliefs. "At least one white supremacist group has reportedly encouraged ghost skins to seek positions in law enforcement for the capability of alerting skinhead crews of pending investigative action against them," the report read. Neither the FBI nor state and local law enforcement agencies have established systems for vetting personnel for potential supremacist links. That task is left primarily to everyday citizens and nonprofit organizations like the Southern Poverty Law Center, one of few that tracks the growing number of hate groups in America.