Testifying at the probe into last year's fatal collapse, Gregory Saunders said he signed off on an inspection report prepared by his partner and fellow engineer, Robert (Bob) Wood, on May 3, 2012.
"We would consider the members still structurally sound," the report stated. "It is our opinion that the observed rusting at this time has not detrimentally changed the load-carrying capacities of the structure, and no visual signs of structural distress were observed."
Seven weeks later, on June 23, 2012, part of the roof-top parking garage at the Algo Centre Mall caved in. Two women were killed and several other people were hurt.
- Watch:Video reveals how Elliot Lake mall collapsed
The judicial inquiry under commissioner Paul Belanger has already heard how the steel support structure — corroded by years of water and salt penetration — finally gave way.
Told it was 'surface rust'
Saunders said he had forgotten signing several reports dating as far back as May 2005 that clearly noted leaks and severe rusting when he reviewed the final inspection document.
He admitted taking no action on the earlier reports, but could not explain why they failed to raise any red flags.
"It's hard to fathom as an engineer that an owner would go through and let leakage last so long," Saunders said.
Wood made no mention of the long-standing leakage, or of a 2009 city order for an extensive inspection of the mall, when he presented the final report, Saunders said.
The two men discussed the inspection, which was required for a mortgage, for about 45 minutes.
Wood told Saunders the maintenance man had walked him around the shopping centre.
"Apparently he checked the worst spots, as far as I know," Saunders said. "We went over the degree of rust. Bob told me it was surface rust."
"Basically, you're taking his word for all of this?" asked commission lawyer Bruce Carr-Harris.
"Yes," Saunders replied.
Asked if it would have made any difference if Wood had brought the long-standing issues about leakage and rust to his attention, Saunders was non-commital.
"It may have been helpful," he said.
'Made some mistakes'
The inquiry also heard how Saunders and Wood, who were partners in M.R. Wright based out of Sault Ste. Marie, Ont., were both found guilty of professional misconduct in 2010 for their work on an unrelated bridge project.
"I made some mistakes in signing off on the drawings," Saunders conceded.
Wood ended up losing his licence after failing to write remedial exams, but Saunders successfully completed his exam work.
It was reported earlier that Saunders lost his engineering licence in relation to the mall's collapse. During testimony at the inquiry Thursday, he said he is a certified professional engineer.
The public inquiry looking at the cause of the roof collapse has been underway in Elliot Lake since March.
Follow CBC Sudbury reporter Amy Dodge's live coverage:
The inquiry was established in July 2012 by the Ontario government to report on events surrounding the mall roof's collapse, and the deaths of Lucie Aylwin and Doloris Perizzolo, as well as the injuries to others and the emergency management and response.
The hearings are expected to conclude with testimony from former premier Dalton McGuinty on Sept. 12.