An autopsy into a New Hampshire inmate who died while awaiting trial on charges that he killed his mother off the coast of Rhode Island to inherit millions of dollars was deemed not suspicious, according to an autopsy report released Wednesday by the New Hampshire attorney general's office.

Nathan Carman, 29, of Vernon, Vermont, was scheduled to go to trial in October for what prosecutors described as a scheme to inherit millions of dollars.

Last year, Carman pleaded not guilty to first-degree murder in the death of his mother, Linda Carman of Middletown, Connecticut, as well as fraud.

Missing Boater

Nathan Carman departs federal court, on Aug. 21, 2019, in Providence, R.I. (AP Photo/Steven Senne, File)

On June 15, as Carman was awaiting trial, he was found dead in a county jail cell in New Hampshire.

The cause and manner of deaths classified as "not suspicious," are not released by the attorney general’s office, spokesperson Michael Garrity told the Associated Press.

Likewise, the U.S. Marshals Service in Vermont said at the request of the family, it would not release Carman’s cause of death.

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Nathan Carman

Nathan Carman died June 15 while awaiting trial in the death of his mother in 2016. (AP Photo/Michael Dwyer, File)

A death is not suspicious when it is determined no crime was committed or nobody else was involved.

Carman faced an eight-count indictment alleging he organized a fishing trip with his mother in September 2016, during which prosecutors claim he was planning to kill her and report she went missing when his boat sank.

Eight days after leaving a Rhode Island marina with his mother, Carman was discovered floating in an inflatable raft. His mother’s body was never recovered.

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The prosecution alleged Carman made modifications to the boat, so it would be more likely to sink, though Carman denied the allegation.

The eight-count indictment also claimed Carman fatally shot his grandfather John Chakalos as he was asleep in 2013, alleging he did so to acquire money and property from his wealthy grandfather’s estate.

The indictment never charged Carman with the death of his grandfather and Carman denied being involved in either death.

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Carman’s attorneys Martin Minnella and David Sullivan had blasted the indictment for making the claim that their client killed his grandfather because he was never charged with the crime.

The Associated Press contributed to this report.