Structural faults led to the fatal collapse of a terminal at the Paris Charles de Gaulle airport last year, an offical inquiry says.
The terminal had been open just 11 months when the roof collapsed
The report by independent engineer Jean Berthier said the concrete roof shell was inherently weak.
The findings are expected to form the basis for the judicial inquiry into the incident. A magistrate must now decide whether charges should be brought.
Four people died when a roof section of terminal 2E collapsed in May.
Parts of the concrete shell of the terminal were cracked before it collapsed, engineer Jean Berthier is quoted as saying by Reuters news agency.
Opened in June 2003
Cost: 750m euros (£500m)
Floor space: 104,000 sq m
Capacity: six million passengers a year
Made from reinforced concrete and 36,000 sq m of glass
Plane parking gates: 10
The 750m-euro ($960m;£516m) building was not designed to support the stress it was put under, and the concrete used in its shell weakened gradually to a point that pillars pierced through it, the report said.
The introduction of a connecting walkway into the side of the terminal created additional strain, Mr Berthier concluded.
The report also says there were problems caused by the rise in temperature under the glass casing.
The report did not apportion blame, but its conclusions will be used as evidence by the investigating magistrate in the case, who will determine whether anyone should be prosecuted.
The terminal, with a capacity for 25,000 people, was conceived as one long concrete tube with no internal supporting pillars, and collapsed less than a year after opening.
French trade unions said at the time that the building work had been rushed. Some feared safety had been sacrificed to create the terminal's daring design.
An initial inquiry following the 23 May collapse found that metal supports had perforated the concrete roof.
Four travellers died, and three were injured when the concrete and glass building caved in.
The terminal partially reopened to traffic three months after the collapse.