Nathan Carman, accused of killing his mother at sea, found dead in his cell at N.H. jail

“He was in excellent spirits,” said Connecticut attorney David Sullivan, adding that he had “a very productive and proactive” call that ended around 7 p.m., and was stunned when he was told Thursday morning that his client was dead.

“We felt like he was going to be acquitted — this is a terrible shock,” said Carman’s other lawyer, Martin Minnella. He said he was notified of Carman’s death by the US Marshals Service, which officially had custody of Carman and placed him at the jail, where pretrial federal detainees for the government are housed.

Carman was found during ”one of the routine inside rounds completed by correctional staff,” according to a statement released by jail superintendent Douglas Iosue and county administrator Chris Coates, announcing his “untimely death.”

A spokesman for the New Hampshire Department of Justice issued a statement saying that the state medical examiner’s office and the Keene Police Department were investigating Carman’s death, which “is not considered suspicious” based on the results of an autopsy.

Carman’s abrupt death marks a tragic end to a case that first captured national attention in 2016 when he was rescued in a life raft 115 miles off Martha’s Vineyard a week after he said his mother died at sea when his boat sank during a fishing trip. The case took a dark turn when court filings showed that police had previously identified Carman as a suspect in the shooting death of his wealthy grandfather in Connecticut three years earlier. His aunts filed a civil suit accusing him of killing both his mother and grandfather in a scheme to inherit millions of dollars.

Police never charged Carman with the slaying of his grandfather, John Chakalos, 87, at his home in Windsor, Conn., in 2013, and his aunts’ suit was dismissed in New Hampshire.

Then, in May 2022, an eight-count federal indictment unsealed in US District Court in Vermont charged Carman with murder on the high seas for allegedly killing his mother, Linda Carman, during their fishing trip, as well as fraud counts related to his effort to obtain inheritance and insurance funds.

The indictment also alleged that Carman shot and killed Chakalos, but didn’t charge him with that slaying, which would be a state crime.

Carman had dinner with his grandfather the night before his death and was the last known person to see him alive, according to a police affidavit. He had purchased a Sig Sauer semiautomatic rifle in New Hampshire that was the same caliber as the weapon used in the shooting, which he did not disclose to police, according to court filings.

Afterward, Carman received approximately $550,000 from his grandfather’s estate, authorities said. But prosecutors allege he killed his mother because he wanted more. Chakalos, a real estate developer, left a $44 million estate to his four daughters, including Carman’s mother.

In September 2016, Carman and his mother set sail from Point Judith, R.I., for a fishing trip. A week later, he was alone when he was rescued from a life raft about 115 miles off Martha’s Vineyard. His mother was never found and is presumed dead.

Prosecutors allege that he deliberately sabotaged the boat as part of a premeditated plan to kill his mother, then claimed it sank accidentally.

On Thursday, the federal case was dismissed at the request of prosecutors, who filed a notice alerting the court that they had been notified by the US Marshal that Carman had died.

“Dismissal of the charges against Carman is thus appropriate,” they wrote.

Fabienne Boisvert-DeFazio, a spokesperson for the US Attorney’s office in Vermont, declined to comment further.

On Thursday, an attorney who represents Linda Carman’s three sisters released a statement saying, “We are deeply saddened to hear of Nathan’s death this morning. While we process this shocking news and its impact on the tragic events surrounding the last several years we ask for your understanding and respect relative to our privacy.”

Carman may never have been indicted on federal charges in the slaying of his mother if not for his effort to collect $85,000 for the loss of his sunken fishing boat. It led two insurance companies to file a suit against Carman to block him from collecting any money, triggering a trial in federal court in Providence, where Carman took the witness stand.

During two days of testimony, Carman said he and his mother were fishing in an area known as Block Canyon off the coast of Long Island, N.Y., when the engine made a strange noise and water began to fill the bilge.

Carman said the boat sank quickly beneath his feet and he cried out for his mother, who was a strong swimmer, but he didn’t see or hear her. He said he managed to make it to a life raft, which had automatically deployed, with a bag of dry clothes and enough food for weeks. A week later he was rescued by a passing freighter.

Several marine experts testified that Carman made the vessel unseaworthy just before setting off with his mother when he removed trim tabs from the rear of the boat, creating four holes just above the water line that he sealed with putty.

Two witnesses also challenged Carman’s claim that his boat sank in Block Canyon and he drifted in a life raft for a week. One specialist said Carman would not have been floating where he was found if the boat sank where he claimed it did. Another expert testified that Carman would have been “profoundly hypothermic if not dead” after a week in the life raft, yet he showed no such symptoms when he was rescued.

On Thursday, attorney David Farrell Jr., who represented the insurance companies during the trial, said he believed the evidence against Carman was so overwhelming that he may have felt trapped, “more trapped than when he was with a sinking boat.”

Shelley Murphy can be reached at shelley.murphy@globe.com. Follow her on Twitter @shelleymurph.