Design blunders by ARCL were fingered as the "primary cause" for the collapse by Mr Mills yesterday in his closing submission.
Today, the commission heard that Holmes Consulting Group (HCG) was instructed to carry out a pre-purchase review of the building in January 1990 as part of due diligence for a prospective buyer.
HCG engineer John Hare identified an area of non-compliance in the connections between the North Shear Core and floor slabs.
The next day, he meet Dr Reay and new ARCL engineer Geoff Banks, to highlight the flaws.
But Dr Reay, according to Mr Mills, failed to reveal the building was designer by David Harding, an engineer inexperienced in multi-storey design.
Mr Mills said it was "inexplicable" that Dr Reay, on learning that Mr Harding had made such a fundament design error, did not call for a full review of the design.
The only possible explanation was Dr Reay's fear of being landed with a major loss claim, he said.
"Subsequent conduct by both Dr Reay and Mr Banks was very clearly influenced by liability concerns, a fact that was acknowledged in cross examination," Mr Mills said.
Remedial work to address the design issues and retrofit drag bars was not completed until the end of 1991.
During the commission, neither Dr Reay or Mr Banks could satisfactorily explain that delay, Mr Mills said, suggesting they were instead "laying low" and hoping the problem might go away.
"The final insult in this sorry saga of minimisation and avoidance was to leave it to the new owner, Madras Equities Ltd, to pay for the remedial work," Mr Mills said.
Expert witnesses told the commission that the drag bars eventually installed in 1991 were, at any rate, were "a poor alternative to a properly designed connection involving a greater contact area between the floor and the webs of the North Shear Core".
Hugh Rennie QC, acting for design firm principal Dr Alan Reay, has now started his final submissions and is expected to conclude later today.