The Southern Poverty Law Center is in the spotlight after the civil rights group announced Tuesday that it is the subject of a U.S. Justice Department criminal investigation because of its past use of paid informants.The center previously used the informants to infiltrate extremist groups, and now faces possible charges over that practice, its CEO Bryan Fair said. The organization has faced credible threats of violence, Fair said, and the information gathered by informants helped saved lives. That information was also frequently shared with the FBI and other law enforcement agencies, he said.The Justice Department had no immediate comment.Here are...