An investigationwas quickly launched to establishhow a routine buildcould have gone so...

[narrator] An investigation
was quickly launched to establish
how a routine build
could have gone so wrong. to establish
how a routine build
could have gone so wrong. The security camera footage
offered investigators
a significant clue. It showed which columns
were the first to collapse. Dr. Jack Leifer is a professor
of engineering. What you see is that
you have those four columns and the four columns
were labeled
in construction diagrams, column O is right up against
the glass facade, then you have P, Q, and R. [narrator] From the footage,
row Q appeared
to collapse first. After inspecting the columns, the team discovered
the alignment bolts
were bent sideways. {\an8}These bolts were key
to lining things up, {\an8}but they weren't designed
to support
the entire structure