(CNN)A 28-year-old man who allegedly killed his mother and grandfather to get family and insurance money was charged with murder and fraud, according to a federal indictment filed in Vermont.
Prosecutors allege he killed his mother to get family and insurance money. He pleaded not guilty
Nathan Carman was arrested Tuesday. He is accused in the death of his mother, Linda Carman, during a 2016 fishing trip off the coast of New England, according to the indictment filed last week in US District Court.
He was found adrift in a life raft a week after their trip began, CNN previously reported. At the time, Carman said there was an unusual noise coming from the engine and then a lot of water in the boat, according to a Coast Guard recording.
"I was bringing one of the safety bags forward, the boat dropped out from under my feet. When I saw the life raft I did not see my mom. Have you found her?" Carman said, according to the recording.
Police had said Carman was being investigated for "reckless endangerment...resulting in death," but he was not charged at the time. Linda Carman's body has not been recovered.
On Wednesday, Nathan Carman pleaded not guilty to fraud charges and a murder charge in connection with his mother's death. He was arraigned in federal court and will be held without bail until his detention hearing, scheduled for for Monday, the deputy clerk of the US District Court in Burlington said.
CNN has reached out to the federal public defender's office representing Carman for comment.
Carman shot and killed his grandfather, John Chakalos, in his Connecticut home in 2013, according to the indictment, but the document contains no murder charge in that death.
Chakalos made "tens of millions of dollars" through real estate ventures, the indictment says. Carman's alleged crimes were "part of a scheme to obtain money and property from the estate of John Chakalos and related family trusts," according to a news release from the US Attorney's Office for the District of Vermont.
Chakalos set up two bank accounts before his 2013 death, one containing about $150,000 for Nathan Carman's college expenses and the other containing around $400,000, with both Linda and Nathan Carman listed as beneficiaries for the latter, according to the indictment.
After spending time with his grandson, Chakalos "convinced" his daughter to designate Nathan Carman as the sole beneficiary of the second bank account, the indictment alleges.
An attorney for Linda Carman has said that grandfather and grandson were very close and that Linda Carman previously insisted her son was not capable of any violence, especially taking the life of someone he loved.
The attorney at the time also noted Linda Carman had said her son was with her fishing at the time the grandfather was killed, contrary to what media reports said.
After Chakalos's death, Nathan Carman received the money from the two bank accounts his grandfather had set up. Between the years of 2014 and 2016, he spent most of it and by the fall of 2016, he was "low on funds," according to the indictment.
On September 17, 2016, he took his mother on a fishing trip, where he allegedly killed her and sank the boat, prosecutors allege. He was rescued by a commercial ship on September 25, according to the indictment.
If convicted, Carman faces a mandatory life sentence for murder on the high seas. Each fraud charge carries up to 30 years in prison, according to a news release from the US Attorney's Office for the District of Vermont.