Polish prosecutors said on Tuesday they would reopen the coffins of all victims of a 2010 presidential jet crash to examine the remains, a move likely to deepen political divisions surrounding the investigation.

The crash near Smolensk, in western Russia, killed 96 people including Poland’s president, Lech Kaczynski, and his wife, as well as the central bank chief, top army brass and several lawmakers.

An inquiry by the previous centrist government returned a verdict of pilot error, but the ruling Law and Justice (PiS) party, led by Kaczynski’s twin brother Jaroslaw, says the crash may have been caused by an explosion on board.

Jaroslaw Kaczynski has also repeatedly accused the then prime minister, Donald Tusk, now head of the European Council, of being indirectly responsible for the crash through negligence.