Turkey has begun the trial of 45 managers and employees charged over a mine disaster which killed 301 people.
Eight of the accused, all senior managers, are charged with murder over the Soma coalmine tragedy in western Turkey last year.
The trial was adjourned until Wednesday because the court said the accused must testify in person, not via video link.
An underground fire sent deadly carbon monoxide through the mine. An inquiry criticised the mine's safety measures.
It was modern Turkey's worst industrial accident.
As the trial opened, exclusive CCTV footage was obtained by the BBC, which showed miners preparing for their shift before the disaster and workers fleeing the scene as it unfolded.
At one point, a desperate miner gestures towards the camera appealing for help. A rescuer is seen kicking a door in frustration at not being able to do more.
The footage is due to be used by defence lawyers when the trial resumes in Akhisar, about 50km (30 miles) from Soma.
Several hundred angry relatives protested outside the special tribunal on Monday, but police prevented them from getting in.
The BBC's Turkey correspondent Mark Lowen says the government is shielding state officials from any investigation, despite claims that they were aware of safety deficiencies at the mine but failed to act.
The managers facing murder charges could be given up to 25 years in prison.
Protests broke out after last year's disaster, fuelled by an apparently insensitive comment by President Recep Tayyip Erdogan, who was prime minister at the time. He said accidents were "in the nature of the business".
The International Labour Organisation says Turkey has the third-highest rate of workplace accidents in the world.