The National Transportation Safety Board released more than 1,600 pages of investigation information on Wednesday related to the Conception dive boat fire that occurred last September.
The documents reveal the moments leading to and following the boat catching fire, including insight from crew members.
Five people survived the 2019 fire, though 34 others died as a result of smoke inhalation in what was one of California’s worst maritime disasters.
The records include factual reports and transcripts from witness interviews. They do not, however, indicate the cause of the fire.
“No physical evidence was recovered that could be identified as an ignition source or indicate a specific ignition location within that area,” the records noted. “Therefore, the cause of the fire is undetermined.”
The records note that there were “numerous electronic devices” being charged on the main level of the boat. Lithium-ion batteries commonly used for computers, cameras and other devices had caused other maritime and aviation fires, officials said.
“It is therefore reasonable to include lithium-ion battery failure as a possible ignition source in this fire scenario,” the report stated. “Another potential source of ignition is the vessel’s electrical system in the salon compartment.”
The fire could have also been caused by an undetermined ignition source, such as discarded smoking materials, authorities said.
The records released this week outline many of the findings from the NTSB’s preliminary investigation, including that five crew members were asleep when the fire broke out despite a requirement that the vessel have a roving watch at night.
The incident remains under investigation by the NTSB, which will hold a public hearing Oct. 20 to announce its findings and recommendations.
A criminal investigation by the U.S. Coast Guard and the FBI under the supervision of the U.S. attorney is also ongoing.