lone gunman

From the Warren Commission's lone gunman theory, that the assassination of U.S. President John F. Kennedy was the work of a single individual, subsequently applied to numerous other political assassinations and shootings.

• "He continues, "So when someone blows the whistle, the hospital has to start looking for a scapegoat. The hospital looks for the lone gunman—the individual, acting alone, acting counter to his training, who, through a gross act of incompetence . . . .""
• "Trial lawyers, always a colorful and eclectic bunch. . . . Most were lone gunmen too eccentric to keep much of a staff."
• "The Wilson family had been sorely conflicted because each member had gone off in his or her own direction, thinking that they were all lone gunmen."

• maverick
• rogue

• march to the beat of a different drum
• scapegoat