Taggart (1983)

Season 18: Episode 4

A student dies when he falls from a roof at a top Glasgow school and a journalist reveals that the death is drugs related. But then the journalist is found dead. He's been having an affair with the paper's editor who becomes chief suspect. When another student dies however, the Strathclyde team discover that a psychopath is on the loose, and he's been under their noses all the time.