On April 10 2010, the Polish President Lech Kaczynski was killed along with 95 others including his wife Maria near the city of Smolensk, Russia.
Both Polish and Russian air crash investigators concluded the tragedy was accidental and happened through pilot error as the plane tried to land in heavy fog.
However some politicians in Poland and experts have claimed that the plane was brought down by two explosions and that Russian air traffic controllers deliberately misled the crew.
Polish defence minister Antoni Macierewicz claimed the Russians had motive for downing the plane, telling the European Parliament last year: "Putin is fully responsible for this tragedy.
"It was the first salvo in a war which today is going on in the east of Europe, and which is ever more dramatically nearing the EU and Nato borders.”