Concord — Nathan Carman’s aunts have asked a New Hampshire court to declare him the killer of his grandfather John C. Chakalos and block his inheritance.

But first a judge must rule on a more prosaic matter: whether Chakalos lived in the state at the time of his death.

A hearing on the topic is slated for May 21, according to an order issued last week by Judge David D. King of 6th Circuit Court District Division in Concord.

Chakalos, 87, was shot and killed in his Windsor, Conn., home in December 2013. A part-time West Chesterfield resident, he left an estate valued at more than $40 million, according to court documents.

The killing remains unsolved. But in a lawsuit filed in July, three of Chakalos’ four daughters alleged Carman killed his grandfather, and therefore shouldn’t benefit from the Chakalos estate — a gambit known as a “slayer action.”

The sisters — Valerie C. Santilli, Elaine Chakalos and Charlene Gallagher — also claim Carman is responsible for the disappearance of his mother, Linda Carman. She went missing in September 2016 during a fishing trip with her son.

Carman has denied involvement in his grandfather’s death and his mother’s disappearance.

Carman, who lives in Vernon, Vt., has sought to have the trust case dismissed. In a Dec. 6 motion, his attorney Richard Thorner argued New Hampshire courts lack jurisdiction over Chakalos’ assets on the grounds that he was not a state resident at the time of his death.

While King won’t rule on the motion until the May hearing, he wrote in the order that the sisters have put forward documentation that appears, on the face of it, to establish Chakalos’ New Hampshire residency.

In an emailed statement, Dan Small, an attorney for the plaintiffs, said, “The Chakalos family is pleased to see Judge King’s statements regarding jurisdiction and thankful that the case and discovery are now moving forward with deliberate speed.”

Carman stands to gain “several million dollars” from his grandfather’s estate, according to his aunts’ petition.

Chakalos and his wife, Rita, who died of natural causes a month before him, owned an 80-acre property in West Chesterfield known locally for its holiday light show. The couple reportedly split their time between that home and the one in Connecticut.

Chakalos was found dead in his home on Dec. 20, 2013. Police in Windsor, Conn., submitted an arrest warrant for Carman in 2014, stating he was the last person to see his grandfather alive, the Hartford Courant reported last year. Prosecutors returned the warrant unsigned due to lack of information, and Carman was not charged.

Santilli and her sisters also allege Carman caused the death of his mother. As Linda Carman’s descendent, he stands to inherit her portion of Chakalos’ estate, according to court documents.

Nathan and Linda Carman set out Sept. 17, 2016, from South Kingstown, R.I., in Nathan’s boat. He was rescued alone about a week later from a life raft.

Nathan Carman later told the U.S. Coast Guard that as his boat sprung a leak and sank, he lost sight of his mother, according to the Courant.

In their petition, however, Carman’s aunts claim he failed to take basic safety precautions. They say he removed trim tabs from the boat, leaving small holes in the hull, and failed to send a distress signal when he should have.