
Five members of one family were shot at a weekend house near Seewen. The killer used a rifle and fired numerous rounds, suggesting preparation and familiarity with the location.
Police pursued family, business, and personal leads and later identified the type of weapon used. A rifle associated with the broader inquiry was recovered years afterward, but the evidence did not establish who committed the killings.
No one has been convicted. The massacre remains one of Switzerland's most notorious unsolved crimes.