Prosecutors have charged 12 people in connection with the deadly 2006 winter roof collapse that killed 65 people at an exhibition hall in southern Poland.

About 500 people were inside Katowice exhibition center hall for an international pigeon fair when the roof buckled and collapsed under heavy, wet snow in January 2006. Rescuers worked frantically in freezing temperatures to try to save those trapped under the wreckage.

After a 2- 1/2 year investigation, prosecutors in Katowice determined that a faulty roof design was the main factor that caused the hall’s roof to collapse, Marzena Matysik-Folga, a spokeswoman for prosecutors there, said Friday.

She said one of the accused had confessed but did not say whom.

The designers of the building were charged with directly endangering lives and could face up to 12 years in prison, Matysik-Folga said.

Two members of the building’s governing board were charged for holding the fair despite knowing the roof was damaged, she said. They face up to eight years, along with seven others who face charges ranging from failing to fulfill their duties to endangering the lives of others.

The building inspector was charged with not fulfilling her responsibilities and faces up to three years in prison.

It was not immediately clear when the trial will start. None of the charged were available to comment.

Sixty-five people died in the accident and more than 140 people were injured.