The black box from the plane which crashed near Smolensk of Russia killing Polish President Lech Kaczynski and 95 other senior officials returned to Poland Thursday afternoon, colonel Jerzy Artymiak from the Polish military prosecutors office told the PAP news agency Thursday.

Investigations into contents of the black box began on Thursday at the Airforce Institute of Technology and are expected to continue during the next few days.

Early reports indicate that the plane made only one attempt to land, according to the head of the Intergovernmental Aviation Committee (MAK), Tatiana Anodina. Previous speculations were the plane may have made up to four attempts to land.

Polish investigators will be joined by Russian member of the commission responsible for investigating the fatal crash.