It wasn't hard to spot the negligence that helped the fire spread so quickly; footage of the EDM venue and art space showed just how cramped and full of flammable material the building was.
Harris was Almena's "creative director", the local newspaper reports, and is accused of planning the December 2 event and blocking off one of two exits as he prepared for it.
The Alameda County district attorney says she will formally announce charges later Monday. "Defendants Almena and Harris knowingly created a fire trap with inadequate means of escape, filled it with human beings, and are now facing the consequences of their deadly actions", said Alameda County District Attorney Nancy O'Malley at a press conference Monday.
"Everything I worked for is gone", Almena posted. The space was home to over a dozen people who used it as an artists' collective. I-Team Reporter Dan Noyes got tipped to the arrest early Monday morning from neighbors who saw it go down. "They send a clear message: you won't get away with making a profit by cramming people into unsafe spaces or failing to maintain safe living conditions".
"We believe that these charges represent no less than a miscarriage of justice and we are confident that this attempt to make a scapegoat out of our client will fail", attorneys Kyndra Miller, J. Tony Serra and Jeffrey Krasnoff said in a joint statement.
O'Malley said Almena and Harris were criminally negligent because they had allowed people to live in the warehouse unbeknownst to the city, fire department and owners, permitting illegal construction and floor-to-ceiling storage that proved highly flammable.
Harris, interviewed two days after the fire, had attributed the blaze to an electrical system that he described as being in disarray. Authorities arrested Almena in Lake County, while Harris was apprehended in Los Angeles.
Relatives of half the victims who died in the fire have filed wrongful death lawsuits against Chor Nar Siu Ng, the building's owner, and Almena, who held the lease.
Almena allowed Harris to live there, calling him the "creative director", who was in charge of collecting rent, mediating disputes and dealing with the building owner.
File - In this December 13, 2016, file photo, flowers, pictures, signs and candles, are placed at the scene of a warehouse fire in Oakland, Calif.
If convicted, Almena and Harris each face up to 39 years in prison.
Firefighters and other city officials were called to the property and adjacent buildings. The two-story warehouse reportedly "had not been inspected in 30 years".
District attorney spokeswoman Teresa Drenick said because of the nature of the fire and "it's consuming almost all of the evidence in that warehouse", the cause of the fire would likely "remain as undetermined".
Between November 2013 and December 2016, police showed up at the warehouse multiple times to check on complaints but Almena and Harris often met police outside the warehouse and told officers that no one lived there, records show.
Harris is accused of renting the upstairs to a dance party promoter on the night of the fire.