A Vermont man accused of murdering his wealthy grandfather and then his mother to collect his inheritance is attempting to access his trust fund.

Nathan Carman, who has Asperger's, was barred from accessing the trust by his aunt who believes the 24-year-old is responsible for the deaths of his rich grandfather, John Chakalos, and his mother Linda Carman.

Carman is now requesting that his aunt, Valerie Santilli, be removed as trustee of the Nathan Carman Family Trust - which was set up for him by Chakalos in 2011 and is worth about $270,000 - after she denied his request for $150,000 for legal expenses.

He says he needs legal representation to defend himself against a slayer lawsuit filed by Santilli and her two sisters, Elaine Chakalos, and Charlene Gallagher, who believe Carman murdered his mother and grandfather to get his hands on a slice of Chakalos' $29 million estate.

The 24-year-old wrote in newly released court documents he had no incentive to murder the man, who had been very generously supporting him financially with housing, schooling and spending money

A slayer suit prevents a person inheriting or profiting from someone their victim's estate. If successful, it would mean prevent Carman, who has not been charged in connection with either death, from ever collecting his $7 million share of the inheritance.

The hearing over Carman's trust fund is set for Tuesday afternoon.

Carman was a suspect in Chakalos' death after the wealthy 87-year-old real estate developer was shot and killed in his Vermont home in 2013, but a prosecutor rejected a warrant for his arrest pending more information.

Three years later, Carman went on a fishing trip with his mother Linda, 54, who disappeared when the boat sank off the coast of Rhode Island.

Carman is still fighting an insurer in federal court who is attempting to avoid paying out its $85,000 policy, claiming that the 24-year-old made suspicious alterations to the boat before it sank.

Nathan Carman was barred from accessing the trust by his aunt who believes the 24-year-old is responsible for the deaths of his rich grandfather, John Chakalos (right)

Chakalos was shot dead in 2013 on the same night he had dinner with Carman, but the 24-year-old was never criminally charged over the death

Meanwhile, Carman has been arguing that he would never have murdered his grandfather because he was a golden goose who would have kept him rich.

Court documents unsealed in May, reveal that Carman had his rent, utilities and education paid for by the multi-millionaire property developer until he was murdered in December 2013.

He claimed that, if anything, he has lost out financially as a result of his grandfather's death.

Carman says as well as the 'love and personal support for each other which my grandfather and I shared in our [familial] relationship', he had been bestowed with countless financial and social benefits.

The 24-year-old had his rent of $2,400, as well as the lease of his furniture - totaling more than $1,000 a month - and utilities including cable television, paid by Chakalos every month. The young man was given a credit card with a $5,000 limit which was paid off every month, and gifted a Nissan pickup truck worth $20,000.

Carman has also been accused of drowning his mother Linda (pictured with him) after their fishing boat sank and he was the only person to make it to a life boat

Carman is the sole heir to his mother Linda Carman, 54, (pictured) who went missing after the trip in September 2016

He claimed Chakalos had also offered to pay his living and educational expenses for the remainder of his schooling before his death, a promise that went unfulfilled as a result of his shooting.

Carman revealed in his statement that his grandfather had initially offered to purchase him a brand new Ford F-150 pickup truck, with a value of $50,000.

He claims the offer was retracted after 'angry and persistent criticism from my aunts Valerie and Elaine', who were upset the value of the car far exceeded the value of a car purchased by Chakalos for his cousin.

Chakalos, a Second World War veteran, was shot dead at his home in Windsor, Vermont in 2013, just weeks after Carman's grandmother died of cancer.

The lawsuit says that a police investigation found Carman had bought a semi-automatic rifle from a gun store in New Hampshire that matched the same caliber weapon used in his grandfather's killing.

The document says he concealed the information from investigators and now says the weapon is missing.

In July 2014, Windsor police submitted an arrest warrant for Carman on a murder charge, but a prosecutor rejected it the next day and returned it with a 'request for further information.'

Carman told the Hartford Courant at the time: 'He loved me very dearly,' he added. 'I was like a son to him; he was like a father to me.'

Carman is also the sole heir to his mother Linda Carman, 54, who went missing after the pair went on a fishing trip in September 2016.

Carman is still fighting an insurer in federal court who is attempting to avoid paying out its $85,000 policy, claiming that the 24-year-old made suspicious alterations to the boat (pictured) before it sank

He was rescued at sea a week later, and t he search for Linda was called off after the Coast Guard said there was no chance of her still being alive.

In a recording of the phone call Carman made to the Coast Guard after he was rescued by a freighter, he said he heard a 'funny noise' in the engine compartment of his boat and then saw water pouring in before he lost sight of his mother.

Carman admitted he'd patched some holes on the 31-foot-long Chicken Pox with marine putty before the trip, he insisted the boat was seaworthy.

But insurance companies claimed in court that 'incomplete, improper, and faulty repairs' were made the day before the boat sank.

Carman later told ABC's '20/20' that he's misunderstood and an easy target for police because he suffers from Asperger's syndrome, a condition on the autism spectrum. A few of its hallmarks are awkward social and communication skills.

Carman has denied killing both his mother and his grandfather, and has not been criminally charged over their deaths.

As police executed a search warrant on his apartment in 2014, one neighbor told police Carman was 'a time bomb waiting to go off', and another referred to him as 'murder boy', based on their personal experience with him.

One officer also spoke with family members, who claimed they were so concerned for their personal safety they had hired private armed security details for their homes.