Swiss police say a man they arrested over the killing of a Swiss air traffic controller lost three members of his family in a mid-air collision.
Most of those killed in the air crash were Russian schoolchildren
They say the suspect's wife, son and daughter died in the accident over southern Germany two years ago.
Seventy-one people - mostly Russian children - died when a Russian charter plane collided with a cargo jet.
The man, believed to be Russian, denies stabbing the controller to death at his home near Zurich on Tuesday.
The suspect's fingerprints will be compared with those found on the suspected murder weapon, police said.
The controller - a 36-year-old Danish national - was in charge of air traffic over Lake Constance at the time of the crash in July 2002.
He was attacked and died on his doorstep, in front of his wife.
Hundreds of Swiss police were involved in the hunt for a man they described as burly, in his early 50s who spoke "broken German".
Train stations, roads and airports were watched.
The controller was stabbed to death in front of his wife at his home
Colleagues of the controller - at the Swiss air traffic agency Skyguide - were in shock at the killing and protection was stepped up for other members of staff.
Skyguide was criticised for its role in the tragedy after investigators revealed that only the one controller was on duty when the collision happened.
He told the pilot of the Russian plane to descend when its onboard collision warning equipment was telling it to climb.
German investigators have said the tragedy was the result of a complex combination of human factors and technical shortcomings.
Last year Germany, Switzerland and Skyguide agreed to set up a fund to compensate relatives of the victims.
They included 52 Russian schoolchildren, most of them sons and daughters of the wealthy elite of the Russian republic of Bashkortostan in the southern Urals region.