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Carrying a bouquet of pink and purple flowers, Nathan Carman met with about a dozen others Wednesday for a private church service in memory of his mother, who is presumed dead after their boat sank in the Atlantic Ocean during a mother-and-son fishing trip.

Absent from the service were his mother's three sisters, who questioned the timing of the event while the sinking remains under investigation by multiple law enforcement agencies.

The memorial for Linda Carman exposed a rift in the family as Nathan Carman says he doesn't know what happened to his mother as the boat sank. He also has denied involvement in the still-unsolved 2013 killing of his 87-year-old grandfather, who left an estate worth more than $42 million to his four adult daughters including Linda Carman.

"Linda's friends and family want to make clear that they are not involved in this event," said Daniel Small, a Boston-based attorney for Linda Carman's sisters. "They believe that it is premature and inappropriate to stage this kind of an event when there is an ongoing investigation into Linda's disappearance."

Nathan Carman, 22, of Vernon, Vermont, organized the service and said he invited his aunts. He said he wanted them to be at the ceremony, and he also held out hope that his mother would still be found.

"I wish very much that my whole family could have come together to pray for my mom," he told reporters after the service. "I'm glad that many of my mom's friends chose to attend, and I think the service was a good time for us to come together and support one another."

Those attending the service at Saint Patrick-Saint Anthony Church included Clark Carman, who is Nathan's father and Linda's ex-husband, as well as some friends of Linda Carman.

Linda Carman, 54, of Middletown, Connecticut, left a marina in South Kingstown, Rhode Island, on Sept. 17 on a fishing trip with her son. He was found alone in a life raft eight days later about 100 nautical miles south of Martha's Vineyard, Massachusetts.

The sinking of the Carmans' 31-foot aluminum boat remains under investigation by federal, state and local law enforcement officials. Nathan Carman told authorities the boat sank in a matter of minutes on the second day of the fishing trip after he heard a "funny noise" in the engine compartment and saw water coming in.

He told The Associated Press last month that he did everything he could to find his mother as the boat went down. He said he blew a whistle and called out frantically for her for hours.

The sinking also put new attention on the 2013 killing of his grandfather, John Chakalos, who was found shot to death at his home in Windsor, Connecticut. Nathan Carman was at one time a suspect in the slaying and authorities have described him more recently as a person of interest. No one has been arrested in the case.

A search warrant said that Nathan Carman was the last person known to have seen Chakalos alive and that he discarded his computer hard drive and GPS unit used around the time of the shooting. The warrant also said investigators learned Carman was "capable of violence" based on past behavior, including when he held another child hostage with a knife.

After the killing, relatives hired armed guards because they were scared of Nathan Carman, according to the warrant.

Carman told the AP last month that he had "absolutely nothing" to do with this grandfather's death.

"My grandfather was like a father to me, and I was like a son to him," he said. "He was the closest person in the world to me, and I loved him and he loved me."