A video shown at the Elliot Lake Inquiry reveals how tragedy struck last June at the Algo Centre mall.

The part-computer animated, part-real security footage video explains, based on forensic engineering, how years of water and road salt had seeped into the mall and worn down its steel structure, leading to the roof collapse that killed two women. A support beam that did not properly connect is also being blamed.

The inquiry has been ongoing since earlier this month. Lawyers have argued that the mall had a lengthly list of structural and leakage problems, and there was ample opportunity to prevent the disaster if only someone had acted.

The inquiry will also examine whether the emergency response to the disaster was adequate. Questions were raised soon after the incident asking whether the emergency operation worked too slowly.

Lucie Aylwin and Doloris Perizzolo died in the collapse on June 23, 2012, and about 20 others were hurt.

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  • Ontario Premier Dalton McGuinty, left, greets people of the community of Elliot lake after speaking at a press conference regarding the rescue and recovery of two bodies at the Algo Centre Mall in Elliot Lake, Ont., on Wednesday, June 27, 2012, after the mall's roof collapse last Saturday. During his address to a small crowd of rescue workers and local officials, McGuinty said his thoughts were with the family of the two female victims, whom he identified as Dolores and Lucie.

  • The Algo Centre Mall in Elliot Lake, Ontario, remains unstable as efforts continue on Wednesday, June 27, 2012, after the mall's roof collapse last Saturday. Officials recovered two bodies after dismantling a piece of a partially collapsed Ontario shopping mall on Wednesday and said they are confident no other victims are inside. The renewed rescue effort came after angry residents shouted down fears that the unstable structure made the work too risky to continue.

  • Firefighters, left, carry a second body out of the Algo Centre Mall in Elliot Lake, Ontario, Canada, on Wednesday, June 27, 2012, after the mall's roof collapsed last Saturday. Officials recovered two bodies after dismantling a partially collapsed Ontario mall on Wednesday and said they don

  • Rescue workers remove their hard hats as firefighters carry a second body out of the Algo Centre Mall in Elliot Lake, Ont., on Wednesday, June 27, 2012, after the mall's roof collapsed last Saturday.

  • Local residents react to the news that rescue workers have recovered a body at the Algo Centre Mall in Elliot Lake, Ont., on Wednesday, June 27, 2012, after the mall's roof collapse last Saturday.

  • Rescue workers wait to access the wreckage of the Algo Centre Mall in Elliot Lake, Ont., early Wednesday, June 27, 2012, as cranes remove debris caused by the mall's roof collapsed last Saturday.

  • Rescue workers watch as a demolition crane tears into part of the Algo Centre Mall in Elliot Lake, Ontario on Tuesday June 26, 2012. The controlled demolition on Tuesday night was part of a renewed bid to rescue any survivors. THE CANADIAN PRESS/Chris Young

  • A monument stands at a road entrance as a demolition crane tears into the Algo Centre Mall in Elliot Lake, Ontario on Tuesday June 26, 2012. Rescue workers are attempting an new plan to search for survivors after the mall's roof collapsed last Saturday. THE CANADIAN PRESS/Chris Young

  • A by-stander reacts as a demolition crane tears into part of the Algo Centre Mall in Elliot Lake, Ontario on Tuesday June 26, 2012. Residents of Elliot Lake, Ontario watched tensely as a massive robotic arm dismantled the facade of a mall that collapsed over the weekend, trapping at least two people inside. THE CANADIAN PRESS/Chris Young

  • Rescue workers watches a demolition crane as it tears into the Algo Centre Mall in Elliot Lake, Ontario on Tuesday June 26, 2012. Rescue workers are attempting an new plan to search for survivors after the mall's roof collapsed last Saturday. THE CANADIAN PRESS/Chris Young

  • A rescue workers watches as a demolition crane as it tears into part of the Algo Centre Mall, in Elliot Lake, Ontario on Tuesday June 26, 2012. Rescue crews began dismantling a partially collapsed mall late Tuesday night in this northern Ontario city in an effort to rescue victims despite fading hopes of finding anyone alive. THE CANADIAN PRESS/Chris Young

  • Local residents react to the news that authorities have called off a rescue bid for any survivors at the site of the collapsed roof of the Algo Centre Mall in Elliot Lake, Ontario, on Monday June 25, 2012 as the site is deemed to dangerous.

  • OPP officers inspect the damage from the roof as rescue workers continue attempts to secure the building before searching for any survivors at the site of the collapsed roof of the Algo Centre Mall in Elliot Lake, Ont. on Monday June 25, 2012.

  • Local residents react to the news that authorities have called off a rescue bid for any survivors at the site of the collapsed roof of the Algo Centre Mall in Elliot Lake, Ontario, on Monday June 25, 2012 as the site is deemed to dangerous.

  • Missing victim Lucie Aylwin's father Rajean Aylwin (centre left) and boyfriend Gary Gendrom (right) react to the news that authorities have called off a rescue bid for any survivors at the site of the collapsed roof of the Algo Centre Mall in Elliot Lake, Ontario, on Monday June 25, 2012 as the site is deemed to dangerous.

  • A rescue worker walks towards the emergency staging post as attempts continue to secure the building before searching for any survivors at the site of the collapsed roof of the Algo Centre Mall in Elliot Lake, Ontario on Monday June 25, 2012.

  • Local residents react to the news that authorities have called off a rescue bid for any survivors at the site of the collapsed roof of the Algo Centre Mall in Elliot Lake, Ontario, on Monday June 25, 2012 as the site is deemed too dangerous.

  • Police form a line outside the Algo Centre Mall in Elliot Lake, Ontario on Monday June 25, 2012. According to some residents a large number of miners are due to arrive from Timmins to join a locally planned rescue effort. Officials in Elliot Lake, Ont., say they are resuming rescue efforts at a partially collapsed mall after an appeal from Ontario Premier Dalton McGuinty.

  • Police officers talk in front of a emergency services tent next to the Algo Centre Mall in Elliot Lake, Ontario on Sunday June 24, 2012.

  • A man leans on a columns next to the collapsed roof of the Algo Centre Mall in Elliot Lake, Ont. on Saturday June 23, 2012.

  • A man leans on a column next to the collapsed roof at the Algo Centre Mall in Elliot Lake, Ont. on Saturday June 23, 2012.

  • A teddy bear with a handwritten note is seen near the Algo Centre Mall in Elliot Lake, Ont. on Sunday June 24, 2012.

  • A woman checks out the damage after a roof collapsed at the Algo Centre Mall in Elliot Lake, Ont., Saturday, June 23, 2012. The partial collapse prompted a local state of emergency and a search for anyone who might have been injured in the cave-in.

  • The roof parking lot of the Algo Centre Mall in Elliot Lake, Ont. is shown on Saturday June 23, 2012.

  • The collapsed roof of the Algo Centre Mall is seen from a nearby hill in Elliot Lake, Ont. on Sunday June 24, 2012.

  • <a href="http://www.youtube.com/watch?v=WLsIqo5aKr8&feature=player_embedded" target="_hplink">Source: YouTube</a>

  • <a href="http://www.youtube.com/watch?v=WLsIqo5aKr8&feature=player_embedded" target="_hplink">Source: YouTube</a>

  • Heavy equipment is used in stabilization and rescue efforts at the Algo Centre Mall in Elliot Lake, Ont. on Sunday June 24, 2012.

  • Elliot Lake -- once an Ontario mining hub -- is located about 160 kilometres west of Sudbury.