Poland’s new ruling conservative party is readying a fresh probe into the 2010 plane crash in Russia that killed President Lech Kaczynski and 95 others.

Separate probes by Polish and Russian aviation experts determined that the crash was an accident. But members of the Law and Justice party that took power last week are saying that the crash resulted from a plot, while the probes were negligent and failed to reveal all the circumstances.

The party leader, Jaroslaw Kaczynski, is the twin brother of the late president. He is insisting on a renewed probe and on a separate verification of the previous Polish investigation.

Justice Minister Zbigniew Ziobro said Thursday that two new probes are “justified.”

Defense Minister Antoni Macierewicz said an investigative commission should be ready next week.