Günther Tschanun – the silent neighbour

Günther Tschanun was a Swiss architect, dancer, seducer, amateur gardener – and mass murderer. In 1986 he shot dead four colleagues in cold blood in Zurich. This film re-tells his story.

This 2023 docufiction by Swiss public television, RSI, re-tells Tschanun’s story from the perspective of Marco, a retired journalist, who discovers that his quiet neighbour, Claudio Trentinaglia, was in fact a former killer.

On April 16, 1986, Günther Tschanun, the head of Zurich’s public construction authority, entered the offices where he worked and shot dead four close colleagues. A fifth colleague was wounded. The killer disappeared before being caught by police three weeks later in southeast France. Why did the 45-year-old architect brutally kill his colleagues?

In 1987, Tschanun was sentenced to 17 years in prison for intentional homicide. A court said the victims were partly to blame for his actions. This bullying theory was later rejected by Switzerland’s highest court. It sentenced him to 20 years in prison for murder and attempted murder.

In 2000, Tschanun was released from prison for good behaviour. After his release he changed his name to Claudio Trentinaglia and lived in canton Ticino. On February 25, 2015, he died in a bicycle accident near Losone.

In the film a former journalist living near Losone is shocked to discover Trentinaglia’s real identity after his accidental death. He decides to find out who his neighbour really was and what caused him to commit the murders over 20 years previously.