BOSTON (CBS) — A young man who was missing at sea for a week was found alive and is expected to arrive in Boston Tuesday–but his mother is missing and presumed dead.

About one week after 22-year-old Nathan Carman of Middletown, Connecticut left Rhode Island on a fishing trip with his mother, Linda, he was found by the freighter Orient Lucky about 100 nautical miles south of Martha’s Vineyard.

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(WBZ-TV)

(WBZ-TV)

The two disappeared September 18 after leaving Point Judith, Rhode Island on a fishing boat named the Chicken Pox.

On Sunday, Nathan Carman was found drifting on an inflatable life raft. Exactly what happened to his mother was not yet known.

“He said that the ship was taking on water, he got the life raft, he looked for his mom to get into the life raft, couldn’t find her, and that’s it,” said Nicole Groll of the Coast Guard.

There was no mayday call and no radio transmission of any kind from the fishing boat, according to the Coast Guard.

(WBZ-TV)

(WBZ-TV)

The Coast Guard does not believe that Linda Carman, 54, could still be alive, so the search for her has been terminated.

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Nathan survived with food and water in the raft, and was said to be in good condition.

“When Nathan Carman comes back to shore, he will be met by Coast Guard officials who will be speaking to him to get a clear understanding of the case,” said Groll.

Linda Carman had told her close friend that she and her son would take the boat out toward Block Island for an overnight fishing trip.

“I’m hoping for lots of answers,” said Sharon Hartstein, a family friend. “I want to know if there’s still hope for Linda, I want to know where they were, and what happened.”

The Chicken Pox. (Photo credit: U.S. Coast Guard)

The Chicken Pox. (Photo credit: U.S. Coast Guard)

The family has had hard times. In 2013, Linda Carman’s father was found shot to death in his Connecticut home.

Nathan Carman has Asperger’s syndrome, a higher-functioning form of autism. Five years ago, he disappeared from his home, upset over the death of his horse, and was found days later in Virginia.

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The Coast Guard said the freighter carrying Nathan is due back in Boston Tuesday night.