(CNN) - Investigators have not determined the cause of the fire aboard the California dive boat that sank last week, a law enforcement official familiar with the investigation said, noting the boat has not even been brought to the surface.
The Conception sank off the Southern California coast on Labor Day following a fire that claimed the lives of 34 passengers.
The official noted that any reporting about the cause would be speculative. Weather conditions have prevented efforts to surface the boat.
The official said authorities are reviewing records obtained during the execution of search warrants in order to determine the Conception's safety record and practices of the operating company.
The Coast Guard Investigative Service on Sunday and Monday served search warrants on Truth Aquatics, the owner of the diving boat that was swallowed up by flames, Santa Barbara County Sheriff's Office spokesman Lt. Eric Raney told CNN on Sunday.
Federal agents also searched the company's boats the Vision and the Truth, officials said.
"This is all just part of the ongoing investigation," Raney said. "The Coast Guard was assisted by ATF, which is investigating the fire and the FBI, which has expertise in criminal investigations."
High winds and strong currents delayed the search and rescue on Monday.
"Reports that the remaining body not recovered is for certain in the boat are inaccurate," Raney said. "We are not sure where that body is. We need to get divers back in the water to search parts of the boat that were unstable during prior searches."
Of the 39 people who were aboard the 75-foot dive boat Conception that weekend, only five crew members were found alive. The others, who were in the lower sleeping deck, likely got trapped when the fire blocked their escape, authorities have said.
Preliminary indications are that the victims' cause of death was smoke inhalation and that the passengers died "prior to being burned," Santa Barbara County Sheriff Bill Brown said Friday.
Thirty-three bodies have been recovered and one remains missing, the sheriff's office said.
Investigation of similar boat led to safety concerns
After investigating a similar boat owned by the same company, National Transportation and Safety Board (NTSB) board member Jennifer Homendy told CNN she has several safety concerns, including whether there is proper equipment for detecting and suppressing fire.
"We're looking into the adequacy of smoke detectors and were there enough fire extinguishers," Homendy said.
The escape hatch in the lower bunk level on the Vision -- the similar boat -- was small and difficult to see, access and maneuver, she said.
The NTSB will be evaluating whether there were "issues with evacuation or responses" or "escape survival factors," Homendy said. She said officials had already interviewed the owner-operator of the dive boat, but didn't offer any further details.
CNN's Ray Sanchez, Stella Chan, Chris Boyette and Theresa Waldrop contributed to this report.
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