The lawsuit against the federal government was filed Tuesday morning by lawyers from the political advocacy group American Civil Liberties Union on behalf of Samaroo’s sister, Sallycar Korasingh, and Joseph’s mother, Lenore Burnley.

Maritime lawsuits can be filed in any federal court in the US, the ACLU noted, and they said they chose Boston because of the long history of such suits here.

The complaint alleges the deaths amount to extrajudicial slayings, or the unlawful killing of an individual by a government.

“I miss him terribly. We all do,” Burnley said of her son, in a statement announcing the lawsuit. “We know this lawsuit won’t bring Chad back to us, but we’re trusting God to carry us through this, and we hope that speaking out will help get us some truth and closure.”

The strike that allegedly took both men’s lives came on Oct. 14, as they made the short journey to the island that’s only a handful of miles off Venezuela’s coast.

For Joseph, according to the lawsuit, it was to be a long-delayed homecoming. The farmer and fisherman had been in Venezuela since April for work, as sometimes happened with him. On top of that, the suit said, he had a hard time finding a boat back to the small fishing village on Trinidad’s north coast where he lived with his common-law wife and three children.

On Oct. 12, he called his wife to tell her the 20-mile boat trip was finally happening: He’d be back in two days, according to the lawsuit.

He’d be with Samaroo, a coworker and fishing buddy who had moved to Las Cuevas a year earlier after his release from prison. He was imprisoned for 15 years for his role in a killing, according to the lawsuit. Media reports say it was the homicide of a street vendor, but don’t provide further detail about what happened.

Samaroo told his sister he was returning on the Oct. 14 boat because he wanted to see their mother, who had fallen ill.

Neither man, their families and the Trinidadian government claim, was involved in the drug trade.

Korasingh, Samaroo’s sister, said he had “paid his debt to society and was just trying to get back on his feet again” when the strike killed him.

“If the U.S. government believed Rishi had done anything wrong, it should have arrested, charged, and detained him, not murdered him,” she said in a statement. “They must be held accountable.”

On Oct. 14, the news came in the form of a social-media post from the president of the United States.

Trump posted that he’d authorized a “lethal kinetic strike on a vessel affiliated with a Designated Terrorist Organization (DTO) conducting narcotrafficking” in international waters near Venezuela. “Intelligence confirmed the vessel was trafficking narcotics, was associated with illicit narcoterrorist networks, and was transiting along a known DTO route.” Six “male narcoterrorists,” Trump said, died in the strike.

If was the latest of what would ultimately be more than 30 such strikes on boats near Venezuela, whose leadership Trump has blamed for the influx of drugs coming into the United States. Ultimately, tensions escalated to the point that US military forces entered Venezuela and arrested its president, the dictator Nicolas Maduro, in a raid earlier this month.

In the Oct. 14 post announcing the strike, the president attached a video of the men’s last moments. A small boat appears to sit in the middle of the frame. Suddenly, a dart of light comes from off the screen above, striking the boat, which explodes into a fireball.

Joseph’s mother, Burnley, saw the reports of the strike on the news and called her son’s wife.

“They immediately feared that Mr. Joseph was aboard this boat, as the timing of the strike directly coincided with Mr. Joseph’s journey by boat from Venezuela to Las Cuevas,” lawyers wrote in the lawsuit.

They called his phone, but it was dead. And, the complaint said, “The line remains dead to this day.”

Their remains were not found. Both families have filed missing-persons reports and sought more information, but non has been available. Both families, according to the lawsuit, have held funerals.

As justification, Trump has said that the US is essentially in conflict with the large drug-trafficking organizations that smuggle drugs into the United States.

In the lawsuit, the families allege the strike was illegal because drug traffickers — even violent ones — do not qualify under international law as an entity that a country can claim it’s in armed conflict against. But even if that were the case, the suit claims, the government should not target civilians.

“As a result, even in the context of an armed conflict, the killings of Mr. Joseph and Mr. Samaroo would constitute a grave breach of the 1949 Geneva Conventions, and thus a war crime, making its perpetrators punishable under federal and international law,” the complaint states.

The lawyers are suing under the century-old Death on the High Seas Act, which allows family members of people killed in international waters to sue for wrongful death.

Ultimately, this suit is seeking unnamed monetary damages for the families. The complaint is not seeking an injunction ordering the government to change its behavior.

Sean Cotter can be reached at sean.cotter@globe.com. Follow him @cotterreporter.