Preliminary findings of an independent investigation into the deadly collapse of a Mexico City metro rail line last month showed the accident was caused by a structural fault, a senior city official said on Wednesday.
Jesus Esteva, head of Mexico City's public works department, said the probe by Norwegian firm DNV observed deficiencies in building materials used including bolts and deformation of structural supports in the part of the line that collapsed.
The initial report by DNV, an external auditor, found "six deficiencies in the construction process" that helped to bring about the accident . . .
