Jennifer Turner, a woman who moved into the warehouse two years before the fire, took the stand late Wednesday.
RELATED: First Ghost Ship trial witness lost daughter in fire
She told jurors that found and ad for the Ghost Ship on craigslist.
Turner says she paid defendant and master tenant Derek Almena $600 for her first month's rent, but moved out a month later.
She is anticipated to testify on behalf of the prosecution Thursday that she moved out because she found the warehouse unsafe.
Day 3 of trial testimony began with the former Oakland Fire Department Assistant Fire marshal, Cesar Avila.
Avila worked for the department at the time of the fire.
The judge deemed him an "expert witness."
Avila outlined fire codes and stringent safety requirements for things like sprinklers and lighted exit signs in buildings used as residences.
A chunk of his testimony focused on whether parking an RV in a building like the Ghost Ship was permissible.
RELATED: Construction worker testifies he warned Ghost Ship was unsafe before deadly fire
Prosecutors say there were 5 RVs and 2 trailers inside the Ghost Ship at the time of the fire.
"No, absolutely no. They are not allowed as living structures in a warehouse. You could have fumes, fuel and propane tanks," testified Avila.
The second half of Avila's testimony focused on whose responsibility it would be if a building's use was changed.
Prosecutors argue that Almena and co-defendant Max Harris leased the building as a warehouse, but then began turning it into a living and assembly space for concerts.
Under their argument, Alemna and Harris would be liable because they should have made the proper upgrades to the facility.
Avila confirmed that point under questioning from Assistant District Attorney Casey Bates.
However, Harris's attorney, Curtis Briggs, argued that the city of Oakland has no records for how the warehouse was originally classified.
RELATED: Defense attorney alleges Oakland Ghost Ship fire was act of arson
"They're trying to say that my client didn't comply with fire code requirements and those are based on what the occupancy classification was but they don't know what the classification was because the city of Oakland has no record of it."
Under cross-examination, Avila admitted to the jury that after the fire he was unable to find records of inspections or citations involving the warehouse.
Almena's attorney Tony Serra told ABC7 News that they still intend to present evidence that the fire was intentionally set by someone other than the defendants.
"You watch we're going to raise reasonable doubt here that it was arson. So all the fire codes in the world are not going to take in to account what you have to do when you have an arson," explained Serra.
Harris and Almena each face 36 counts of involuntary manslaughter in the fatal December 2016 warehouse blaze.
Testimony continues Thursday in Oakland.
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