A Vermont man has died in custody while awaiting trial on charges of killing his mother at sea, federal authorities said on Thursday. Nathan Carman, 29, was accused of the first-degree murder of his mother Linda Carman during a 2016 boating trip in what prosecutors alleged was a plot to inherit millions of dollars. Carman pleaded not guilty last year to fraud and first-degree murder and had been due to go on trial in October. The cause of his death was not immediately known. In September 2016, Carman arranged a fishing trip from a Rhode Island marina with his mother, during which his boat reportedly sank and his mother disappeared. Carman was found floating in an inflatable raft eight days later, while his mother has never been found. Prosecutors allege that Carman made alterations to the boat to make it more likely to sink. He was also accused of killing his grandfather, John Chakalos, who was shot dead in his home in Windsor, Connecticut, in 2013. Chakalos’s killing was part of a scheme by Carman to obtain millions of dollars from his grandfather’s estate, according to an eight-count indictment. He had not been charged in that case. Chakalos had made a fortune of tens of millions of dollars by building and renting nursing homes. Last May, Carman was arrested and charged with his mother’s murder. Prosecutors urged him to be held in custody pending trial as he was a flight risk. Carman was being held by US Marshalls at the time of his death. His attorney Martin Minnella told the Associated Press that he had been in good spirits when they spoke on Wednesday, and they had been due to meet again on Thursday. “We were meeting with some experts today over Zoom at 12 o’clock. We were prepared to start picking a jury on October 10 and we were confident we were going to win,” he said. “It’s just a tragedy, a tragedy.” According to prosecutors, Carman’s inheritance scheme began nearly a decade ago when he purchased a rifle in New Hampshire and used it to shoot Chakalos while he was asleep in his Connecticut home on 20 December 2013. Carman then discarded his own computer hard drive and the GPS unit that had been in his truck, according to the indictment. After his grandfather’s death, Carman received $550,000. He moved from Bloomfield, Connecticut, to Vernon, Vermont, in 2014, was unemployed, and by 2016 had squandered most of his inheritance, they alleged. He then organised the fatal boating trip with his mother Linda, of Middletown, Connecticut. In 2019, Chakalos’ three surviving daughters filed a lawsuit in New Hampshire seeking to block Carman from receiving any more of his grandfather’s inheritance. The case was dismissed after a judge ruled that Chakalos was not a New Hampshire resident. It was later refiled in Connecticut and was still pending. The three sisters issued a statement to the AP saying they were “deeply saddened” by Carman’s death. “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,” they said through a lawyer. Read More Man charged with murdering mother on fishing boat to inherit grandfather’s riches Man found on raft after mother's mystery death at sea was suspect in grandfather's killing Treat Williams death: Everwood and Hair star dies aged 71 following motorcycle accident