Blood Relatives (original French title: Les liens de sang) is a 1978 Canadian-French mystery film directed by Claude Chabrol from a screenplay that he and Sydney Banks adapted from the 1975 novel of the same name by Ed McBain.

[1] Set in Montreal, Canada, it involves the brutal murder of a teenage girl and the subsequent investigation led by Donald Sutherland as Steve Carella, the lead character of McBain's 87th Precinct series.

[4] One rainy night a teenage girl named Patricia staggers wounded into a police station saying that she and her older cousin Muriel, who lived in her family home, had been brutally attacked with a knife in a dark alley.

A possible clue comes at the funeral, when Patricia's brother Andrew in grief throws himself on the coffin of his dead cousin.

After repeated lying, the girl admits that she was lethally jealous of the sexier Muriel, who she felt had stolen the love of her brother.