What happened
On April 16, 1986, Günther Tschanun, a 45-year-old architect who headed Zürich's public construction authority, entered the municipal offices where he worked and shot five colleagues. Four died and a fifth survived with serious injuries. Tschanun left Switzerland and was arrested about three weeks later in southeastern France.
The court proceedings
In February 1988, the Zürich Higher Court convicted Tschanun of four counts of intentional homicide and imposed a 17-year sentence. Prosecutors challenged that classification. In January 1990, Switzerland's Federal Supreme Court set the judgment aside and required the killings to be treated as murder. On August 31, 1990, the Zürich Higher Court imposed a 20-year prison sentence for murder and attempted murder.
Motive and responsibility
Contemporary proceedings focused heavily on a bitter workplace conflict. The first judgment had treated conflict with the victims as partially mitigating. The Federal Supreme Court rejected that approach. Prosecutors had described the attack as a deliberately prepared plan against colleagues Tschanun believed were undermining him; that description is an allegation from the charging record, while the final legal result was the murder conviction.
Later life
Tschanun was conditionally released in January 2000 after serving about fourteen years. He adopted the name Claudio Trentinaglia and lived in canton Ticino. Swiss public broadcaster reporting based on his corrections-system file later established that he died on February 25, 2015, in a bicycle accident near Losone.
Sources and further reading
Case context
The Zürich office murders remain one of Switzerland's most widely remembered workplace killings. The court history is especially notable because the Federal Supreme Court rejected the earlier mitigating theory and required a murder conviction.