LOS ANGELES (AP) — A federal jury on Monday found a scuba dive boat captain was criminally negligent in the deaths of 34 people killed in a fire aboard the vessel in 2019, the deadliest maritime disaster in recent U.S. history.

The U.S. Attorney’s Office in Los Angeles confirmed Jerry Boylan was found guilty of one count of misconduct or neglect of ship officer, a pre-Civil War statute colloquially known as seaman’s manslaughter that was designed to hold steamboat captains and crew responsible for maritime disasters. Boylan was the only person to face criminal charges connected to the fire.

He could get 10 years behind bars.

The verdict comes more than four years after the Sept. 2, 2019, tragedy, which prompted changes to maritime regulations, congressional reform and civil lawsuits.

The Conception was anchored off the Channel Islands, 25 miles (40 kilometers) south of Santa Barbara, when it caught fire before dawn on the final day of a three-day excursion, sinking less than 100 feet (30 meters) from shore.

Thirty-three passengers and a crew member perished, trapped in a bunkroom below deck. Among the dead were the deckhand, who had landed her dream job; an environmental scientist who did research in Antarctica; a globe-trotting couple; a Singaporean data scientist; and a family of three sisters, their father and his wife.

Boylan was the first to abandon ship and jump overboard. Four crew members who joined him also survived.

Although the exact cause of the blaze remains undetermined, the prosecutors and defense sought to assign blame throughout the trial.

The U.S. Attorney’s Office said Boylan failed to post the required roving night watch and never properly trained his crew in firefighting. The lack of the roving watch meant the fire was able to spread undetected across the 75-foot (23-meter) boat.

Boylan’s attorneys sought to pin blame on boat owner Glen Fritzler, who with his wife owns Truth Aquatics Inc., which operated the Conception and two other scuba dive boats.

They argued that Fritzler was responsible for failing to train the crew in firefighting and other safety measures, as well as creating a lax seafaring culture they called “the Fritzler way,” in which no captain who worked for him posted a roving watch.

Two to three dozen family members of the victims attended each day of the trial in downtown Los Angeles. U.S. District Court Judge George Wu warned them against displaying emotion in the courtroom as they watched a 24-second cellphone video showing some of their loved ones’ last moments.

While the criminal trial is over, several civil lawsuits remain ongoing.

Three days after the blaze, Truth Aquatics filed suit in U.S. District Court in Los Angeles under a pre-Civil War provision of maritime law that allows it to limit its liability to the value of the remains of the boat, which was a total loss. The time-tested legal maneuver has been successfully employed by the owners of the Titanic and other vessels and requires the Fritzlers to show they were not at fault.

That case is pending, as well as others filed by victims’ families against the Coast Guard for alleged lax enforcement of the roving watch requirement.