Police in Poland have arrested three men who designed an exhibition hall that collapsed in January, killing 65 people.
Snow and freezing weather hampered the search for survivors
Two of the men have been charged with intentionally allowing an accident that endangered lives and the third with a lesser crime, prosecutors say.
Some 500 people were in the Katowice trade hall for a pigeon exhibition when the roof caved in under heavy snow.
The accident, Poland's worst building disaster, also injured 140 people.
"The designers disregarded building regulations. The project and its realisation were faulty," said Tomasz Tadla, a spokesman for Katowice prosecutors.
The arrests follow a report issued in May, which pointed to "design and construction errors" as possible causes for the building collapse.
Three managers of the company that maintained the hall have been in police custody since February on suspicion of negligence.