Roche and Little, both of whom worked at the mill, were killed and 24 others were injured in the sawdust-fuelled explosion and ensuing fire in April 2012.
The inquest, being heard by a seven-person jury, is meant to publicly review the facts around the explosion.
On Monday, Ronda Roche, who lost her husband in the explosion, and Joanna Burrows, Little's common-law spouse, addressed the inquest.
Burrows told the court that there was a stressful environment at the mill leading up to the explosion. She said Little had been grinding his teeth in his sleep and that productivity was a priority.
Brian Primrose, who worked at the mill with Roche and Little, also testified. He said he was increasingly concerned about sawdust and fires at the mill before the explosion.
About 50 witnesses are expected to take the stand at the inquiry, which it is anticipated will run for about three weeks in Prince George.
'Deaths...aren't going to be covered up'
Speaking before the inquest opened Barb McClintock, with the B.C. Coroners' Service, said the inquest should let the public know exactly what happened.
"[It] reassures them that deaths of any members of their community are going to be taken seriously and aren't going to be covered up," McClintock said.
Lakeland Mills Ltd., the company that owned the mill, was fined $724,000 by WorkSafeBC last July, but appealed the decision.
No criminal charges were laid after Crown counsel concluded in 2014 that WorkSafeBC's investigation didn't properly gather evidence to determine to what extent management was aware of the risk of an explosion from sawdust accumulation.
The mill re-opened in December after being entirely re-built.
An inquest into two more deaths at the Babine Forest Products sawmill in Burns Lake, B.C., — also in 2012 — is scheduled to start in July.