LOS ANGELES (NewsNation Now) — The captain of a scuba diving boat that burned and sank off the California coast, killing 34 people, pleaded not guilty Tuesday to manslaughter charges.

Jerry Boylan was arraigned in federal court in Los Angeles on 34 counts of seaman’s manslaughter. Each count carries a potential 10-year prison term.

Prosecutors say Boylan failed to follow safety rules before the fire broke out Sept. 2, 2019, on the Conception and led to one of the deadliest maritime disasters in recent U.S. history.

The Conception was carrying 33 passengers on a Labor Day weekend scuba diving expedition near an island off Santa Barbara. The fire broke out while passengers were sleeping and quickly swept through the vessel.

Boylan was accused of “misconduct, negligence and inattention” by failing to train his crew, conduct fire drills and have a roving night watchman on the boat when the fire ignited.

Boylan, 67, was indicted in December and surrendered for booking Tuesday morning. He was held in lockup and appeared in court by video wearing a blue surgical mask. He was expected to be released later on a $250,000 bond.

The rare federal charges against Boylan were brought under a pre-Civil War law designed to hold steamboat captains and crew responsible for maritime disasters that were much more frequent at the time. Each count carries a possible 10-year prison term with conviction.

Boylan and four other crew members, who had all been sleeping, escaped from the fiery boat after the captain made a panicked mayday call.

Boylan spoke very little during the short hearing, responding to Magistrate Judge Jean Rosenbluth’s questions with “not guilty” and short answers.

All 33 passengers and one crew member died in the bunkroom below deck, some wearing shoes that led to speculation they were trying to escape. Officials said they were trapped by flames that blocked a stairwell and a small hatch that were the only exits. All died of smoke inhalation, according to coroner’s reports.

The 34 victims ranged from a new deckhand to scientists and engineers to parents with their teenage and adult children. They came from as far away as China, Singapore, and India. Two passengers were celebrating birthdays.

The sole crewmember who died, Allie Kurtz, 26, had previously worked as a cook on another Truth Aquatics boat and was thrilled with her promotion. Her family said she loved the water and had childhood aspirations of becoming a pirate.

Family members of Charles McIlvain and Justin Dignam, among other relatives, watched the proceeding on video from a separate courtroom. Some families listened in by telephone. Rosenbluth apologized they couldn’t be in same courtroom but said she recognized their presence at the hearing.

“We’re here today to honor his memory and to represent the families of all 34 victims,” Kathleen McIlvain said outside court after the short hearing. “We hope this is the beginning of the journey to find justice for our loved ones.”

Federal safety investigators blamed the owners of the vessel, Truth Aquatics Inc., for a lack of oversight, though they have not been charged with a crime.

Truth Aquatics has sued in federal court under a provision in maritime law to avoid payouts to the families of the victims. The families of 32 victims have filed claims against boat owners Glen and Dana Fritzler and the company. The Fritzlers and the company in turn have filed a legal claim to shield them from damages under a maritime law that limits liability for vessel owners.

The cause of the fire was under investigation for more there a year and may be impossible to pinpoint. It began in an area on the main deck where divers had plugged in phones, flashlights, and other items with combustible lithium ion batteries, according to the National Safety Transportation Board.

NTSB investigators condemned the company and captain for a litany of issues including failing to train the crew on emergency procedures. The agency also said the lack of a night watch allowed the fire to spread quickly and trap victims below deck. The NTSB also faulted the Coast Guard for not enforcing the night watch requirement, citing records showing no one cited for failing to provide one since 1991.

Reporting by Stefanie Dazio and Brian Melley. The Associated Press contributed to this report.