The change was in perception rather than reality, but it still had significant consequences for reactions to violent crime by both law enforcement and the media. Linkages between individual murder cases were more likely to be suggested, and the police were more likely to postulate the existence of unknown serial killers. This article examines this trend with special reference to three major cases in the mid-1980's: the "Railway Murders" and two probable series of child killings originally investigated under the general title of "Operation Stranger." The origins of the new attitude toward multiple homicide was sought both in American influences and contacts as well as in the internal politics of the British police. Issues of national policing and centralized intelligence gathering are emphasized. 3 tables and 51 references (Author abstract modified)