Portland fire and police investigators are still working to determine what sparked the Aug. 2 four-alarm fire that gutted the 116-year-old Centennial Mills warehouse, with two neighborhood theories gaining traction as a Friday, Aug. 14 demolition deadline approaches.
The Portland Fire Investigations Unit, a joint team of Portland Fire & Rescue and Portland Police Bureau personnel, has not named a cause.
But in the Pearl District, residents are pointing to two possibilities: homeless squatters who had repeatedly broken into the boarded-up building, and a possible act of arson targeting building owner Stuart Lindquist over his ties to a U.S. Immigration and Customs Enforcement facility.
Neither theory has been confirmed by investigators.
A history of break-ins
The warehouse at 1362 NW Naito Parkway had long been on PF&R's "unsafe building" list. Pearl District Neighborhood Association president Bruce Studer told KGW in July that the building had repeated issues with squatters and homeless campers, sometimes prompting fire department responses. Portland police posted video roughly a month before the fire showing officers clearing squatters from the building and arresting one person.
PF&R spokesperson Rick Graves told the Northwest Examiner on Aug. 3, the day after the fire, that "transients have occupied the building even though it is boarded up."
Kevin Dahlgren, who runs the blog Truth on the Streets and has documented homeless activity in the area, told the Northwest Examiner on Aug. 5 that the city had "repeatedly re-shielded the windows and doors because people break inside."
Anti-ICE posters raise second theory
Pearl District resident Karla Powell offered investigators a different lead. In an email to the Northwest Examiner published Aug. 5, Powell said anti-ICE anarchist posters were distributed near the warehouse shortly before the fire. Lindquist, who bought Centennial Mills for $1.25 million in 2024, also owns the South Waterfront building leased by ICE.
The Portland Design Commission had approved his 2025 plan to convert the site into three mid-rise buildings with 272 residential units, retail and a nightclub.
Powell said she is "highly suspicious it was torched by this group in an attempt to bring down Stuart Lindquist." No law enforcement agency has publicly confirmed the posters as evidence or a lead in the investigation.
Investigators ask for public help
The Fire Investigations Unit is asking anyone who captured video or photos near the site at approximately 3:50 p.m. on Sunday, Aug. 2 to upload them through a dedicated portal. Detectives said submitters do not need to review or edit footage and will be contacted only if follow-up is needed.
The Scappoose Fire District Aviation Team used a drone to create a 3D map of the damaged interior to help pinpoint the fire's origin.
Possible human remains complicate timeline
An initial K9 sweep on Monday, Aug. 3 returned negative results. But two follow-up sweeps on Thursday, Aug. 6 both returned positive alerts for human remains inside the rubble. PF&R said in a press release on Friday, Aug. 7 that investigators believe there is a "high likelihood" human remains are present within the structure.
Portland Permitting & Development issued a demolition order to Lindquist on Aug. 6, directing him to begin tearing down the building no later than Friday, Aug. 14. PF&R has said the demolition is expected to play a critical role in the investigation by removing unstable hazards around the areas flagged by K9 teams. Spokesperson Graves warned on Aug. 5 that a collapse before controlled demolition would make the forensic process "far more difficult."
Northwest Naito Parkway remains closed between NW 9th and 15th avenues, and a 150-foot safety perimeter surrounds the building, also affecting the adjacent Union Pacific and BNSF freight rail corridor. Demolition must begin by Friday.
