WARSAW — The bodies of Poland’s former president and his wife were exhumed Monday evening as part of an investigation into an April 2010 plane crash in Russia that killed the couple — after years of speculation, backed by little evidence, that the crash was not an accident.

Over the next two months, prosecutors appointed by Poland’s right-wing governing party plan to examine the remains of 83 of the 96 people who died in the crash, starting with the former president, Lech Kaczynski, and his wife, Maria. The couple’s bodies were interred in a crypt in a cathedral in Krakow, near the tombs of Poland’s kings and heroes like the military commander Thaddeus Kosciuszko and the poet Adam Mickiewicz.

Jaroslaw Kaczynski, the former president’s twin brother and the leader of the ruling Law and Justice Party, was on hand for the ceremony, at the Wawel Cathedral.

The party has long insisted that investigations by Poland’s former government and the Russian authorities failed to unearth the true cause of the crash. Reopening the investigation was one of the first acts of the new government after assuming power a year ago.