FILE - This Sept. 27, 2016 file photo shows Nathan Carman arriving in a small boat at the US Coast Guard station in Boston. Carman's family filed a lawsuit in New Hampshire on Monday, July 17, 2017 accusing him of killing his grandfather and possibly his mother, who was lost at sea during a mother-son fishing trip. Carman denies in court papers allegations that he killed his millionaire grandfather in 2013. (AP Photo/Michael Dwyer)

CONCORD, N.H. - A Vermont man denied in court papers Wednesday allegations that he killed his millionaire grandfather in 2013 and claims he doesn't know the whereabouts of his mother who disappeared after a boat they were on sank off Rhode Island.

Nathan Carman has been called a suspect in the shooting death of 87-year-old real estate developer John Chakalos in Connecticut. No one's been arrested.

He has also been questioned about the day his boat sank with his mother, Linda Carman, on it. She's presumed dead. He said he doesn't know if anyone has seen his mother since their fishing trip in 2016.

In July, the three sisters of Linda Carman filed a lawsuit in New Hampshire accusing Nathan Carman of killing Chakalos and possibly his mother. They've asked a judge to block Nathan Carman from collecting money from his grandfather's estate. Chakalos left more than $29 million to his four daughters, including Linda Carman, and $7 million of that money could go to Nathan Carman.

The sisters' attorney, Dan Small, has said all the evidence points to Nathan Carman as the killer. If the family wins the lawsuit, Small has said any money that would have gone to Carman would go to investigate the death of John Chakalos and Linda Carman.

Nathan Carman on Wednesday moved to dismiss the lawsuit, saying Chakalos wasn't a resident of New Hampshire at the time of his death.

The family on Wednesday insisted in a statement that Chakalos was a "long time resident of Chesterfield, New Hampshire, and a well-known, active member of the community."

"The groundless claims and denials contained in Nathan Carman's response filing do not reflect reality, and we are confident the legal process will recognize this," Small said.

In the sisters' lawsuit, lawyers for the family said that no has seen Linda Carman since she boarded the boat, the Chicken Pox, with Nathan Carman. In their motion to dismiss, lawyers for Nathan Carman said he "lacks sufficient information to either admit or deny" that he was the last to see his mother.

Nathan Carman has acknowledged that he patched some holes on the 31-foot-long boat with marine putty before going fishing with his mother but insisted the boat was seaworthy. Insurance companies claimed in court earlier this year that "incomplete, improper, and faulty repairs" were made the day before the boat sank.

News from © The Associated Press, 2017