WARSAW, Poland (AP) — The remains of Polish President Lech Kaczynski, his wife and other victims of a 2010 plane crash will be exhumed to help investigators determine the cause of the crash that killed 96 people, a spokesman for top prosecutors said Wednesday.

Prosecutor Maciej Kujawski told The Associated Press that investigators are in talks with Polish and foreign experts who they want to carry out the exhumations at an unspecified time. Temperatures in Poland allow for exhumations to take place from mid-October until mid-April.

Kujawski said the autopsy documents that Poland received from Russia, where the crash occurred, are incomplete and in some cases erroneous and don't help explain the reason for the crash, which is under a renewed investigation in Poland. Doubts raised by the documents have led to nine exhumations in previous years. In six cases the bodies were found to have been mixed up. The bodies arrived from Russia in sealed coffins and no examinations took place in Poland.

Kaczynski's plane crashed April 10, 2010, in dense fog on approach to Smolensk airport. Separate commissions of aviation experts in Poland and in Russia blamed the crash on insufficient training of the crew and on human error in adverse circumstances.

A new investigation was launched this year by the government of the Law and Justice party that is led by Kaczynski's twin brother, Jaroslaw Kaczynski.

Some Law and Justice members claim the crash was an assassination and was caused by explosives placed onboard the plane, by forces in Poland and in Russia. The investigators also take this hypothesis into account.

Russia has not returned crucial evidence — the flight recorders and the wreckage — saying it still needs them for its own criminal investigation into the crash.

The exhumation decision was taken Tuesday during a meeting with the families of some of the victims, including Jaroslaw Kaczynski.

On Tuesday, a Warsaw court convicted a former deputy head of government security of neglecting the security of the president's flight and handed him an 18-month suspended prison term.