A 29-year-old Vermont man charged with killing his mother in a plot to inherit millions of dollars died in jail this week in New Hampshire.

Nathan Carman pleaded not guilty to fraud and murder charges in the 2016 death of Linda Carman, who was lost at sea off the coast of New England during a fishing expedition organized by her son, and was set to go on trial in October, the Associated Press said.

An eight-count indictment against Carman also accused him of shooting to death his wealthy grandfather, John Chakalos, as he slept in 2013 but did not charge him with that crime.

Carman was the sole occupant of a county jail cell in a facility run by the Cheshire Corrections Department. He was found dead at about 2:30 a.m. Thursday, according Doug Losue, superintendent of the department. His cause of death was not immediately clear.

One of his attorneys, David Sullivan, told the AP that Carman left a note for his attorneys, but they didn’t yet know what it said. Federal prosecutors told them about the note, he said.

With the death of his mother and grandfather, Carman stood to inherit around $7 million, his mother’s share of her father’s estate. But his surviving aunts had challenged the inheritance.

Chakalos’s surviving daughters said in a statement they were “deeply saddened” to learn of their nephew’s death, asking for privacy “while we process this shocking news and its impact on the tragic events surrounding the last several years.”

Police drafted an arrest warrant charging Carman with his grandfather’s death in 2014, but a prosecutor refused to sign it, requesting more information, which was never forthcoming. Carman’s attorneys filed documents in 2018 claiming Chakolos’s “mistress” was more likely to have killed him.

But prosecutors say Carman bought a rifle, similar to the one used in his grandfather’s shooting, which disappeared, along with his computer’s hard drive and his truck’s GPS unit, after the shooting. Carman, who was largely unemployed until his arrest, inherited $550,000 after his grandfather’s death, but when that money ran out, they said, he organized the fishing trip with his mother.

As CrimeOnline previously reported, the Coast Guard rescued Carman from an inflatable raft after his boat sank off the coast of Rhode Island. His mother’s body was never recovered.

Prosecutors alleged that Carman rigged the boat to sink and took his mother much further out into the ocean than she wanted to go or expected.

The indictment apparently came out of an insurance company’s investigation into Carman’s claim for the loss of his boat. The insurance company’s investigation laid out a case that Carman had planned both murders. A judge also sided with the insurers.

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[Featured image: FILE – Nathan Carman departs federal court on August 21, 2019, in Providence, Rhode Island. (AP Photo/Steven Senne, File)]