SANTA BARBARA, Calif. (AP) — Dozens of people trapped on a scuba diving boat that caught fire off the Southern California coast appear to have died from smoke inhalation, not burns, authorities said Friday.

“The indicators are from the preliminary examination of the bodies that the victims died prior to being burned,” Santa Barbara County Sheriff Bill Brown said. “The burn damage to the victims was post-mortem.”

More than half the 34 people killed as they slept in bunks below deck early Monday have been positively identified through DNA, and their family members around the world are being notified, Brown told reporters. Divers are searching for the one body that still has not been found.

Five crew members jumped overboard after trying to rescue the 33 scuba divers and one crew member whose escape routes were blocked by fire, federal authorities and the boat’s owner said. The crew, including the captain, said they were driven back by flames, smoke and heat.

Multiple investigations into the disaster are focused on determining what happened and have not become a criminal probe, though Brown said charges are possible.

Notifying families that their loved ones were aboard the Conception and gathering DNA to identify remains burned beyond recognition has taken an extraordinary worldwide effort.

A mother in Japan was told Thursday that her child was on the boat. The FBI also had to deliver the news to a family in Singapore and relatives from India who flew into California, Brown said.

The remains of 18 people have been positively identified, and the sheriff released the names of nine whose families have been notified.

A salvage crew working with the Coast Guard was trying to recover the ship that sank in 60 feet (18 meters) of water off the rugged Channel Islands, where the boat took a three-day excursion.

Speculation has grown about whether the captain and four other crew members who survived had tried to help the others before jumping from the flaming vessel. But they said that by the time they saw flames, it was too late.

The crew members told investigators a “harrowing story” about the moments after the blaze erupted before dawn Monday as it lay at anchor, Jennifer Homendy of the National Transportation Safety Board said Thursday.

They jumped from the bridge area to the main deck — one breaking a leg in the effort — and tried to get through the double doors of the galley, but they were on fire.

That cut off both escape routes from the sleeping quarters: a stairway and an escape hatch that exited in the galley area. The crew then tried, but failed, to get into windows at the front of the vessel.

“At that point, due to heat, flames and smoke, the crew had to jump from the boat,” Homendy said.

Captain Jerry Boylan stayed aboard trying to send radio distress calls and was last in the water, said Glen Fritzler, co-owner of Truth Aquatics Inc. of Santa Barbara, which operated Conception.

“The other crew at a certain point when the flames had engulfed the boat and they were in the water, they could see Jerry jump from the upper deck, a long jump. And there was a trail of smoke following him. They thought he was on fire,” Fritzler told KEYT-TV in Santa Barbara.

“Within minutes, they would’ve been consumed,” he said. “So they did their best. They did re-enter the vessel from the back of the boat after they swam around it. They could not get to firefighting equipment because everything was engulfed.”

The survivors used a skiff at Conception’s stern to reach a nearby boat, and two of them then returned to see if they could rescue any other survivors, Homendy said. They found no one.

Fritzler said the experience has traumatized the survivors.

“They’re breaking down,” he said. “They’re seeking counseling. It’s a very tough time for them.”

Meanwhile, Truth Aquatics filed a lawsuit Thursday in federal court that uses a pre-Civil War provision of maritime law to limit their liability from any victims’ claims. The lawsuit argues that the company and its owners made the boat seaworthy and it was properly manned and equipped.

Coast Guard records show the boat passed its two most recent inspections with no safety violations. And previous customers said Truth Aquatics and the captains of its three boats were very safety conscious.

The NTSB is just a few days into what will be a lengthy investigation that seeks to determine the fire’s cause and identify potential safety enhancements to avoid future disasters.

Investigators are examining potential ignition sources for the fire, including electronics, kitchen stoves and the vessel’s wiring systems. Investigators know photography equipment, batteries and other electronics were stored and plugged in on the Conception.

“We are not ruling anything out at this point,” Homendy said.

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Associated Press writers John Antczak and Brian Melley in Los Angeles, Julie Watson in San Diego and Amy Taxin in Santa Ana, California, contributed to this story.