Robert Nazarian is expected to face questions about what he knew about the state of the mall and what he did about it.
The immigrant from Iran is expected to say the previous owners hid the fact the building was a lemon.
Nazarian's son, Levon, testified last week they plowed money into stop-gap repairs while they tried to sell the mall or raise cash for a proper fix.
However, he said the bank and city thwarted their best efforts to remedy the financially ruinous situation.
The public inquiry was established in July 2012 by the Ontario government and has been underway in Elliot Lake since March.
It was created to report on events surrounding the mall roof's collapse on June 23, 2012, the deaths of Lucie Aylwin and Doloris Perizzolo, the injuries to others, and the emergency management and response.