BOSTON (CBS) — A man who was rescued after spending a week at sea in a life raft was debriefed by the Coast Guard Tuesday in Boston after the search for his mother was called off. Authorities also searched his home for clues.

Nathan Carman, 22, arrived safely at a Coast Guard base in Boston Tuesday morning, though his mother, Linda Carman, 54, has not been found and is presumed dead.

READ MORE: More Than 495,000 Lose Power As Nor'easter Hits Massachusetts

Just what happened to Linda Carman was not yet known. A search warrant was executed Monday night at Nathan Carman’s Vernon, VT home. Officers seized a modem, a Garman SIM card and a letter written by Nathan.

Nathan and his mother disappeared September 18 after leaving Point Judith, Rhode Island on a fishing boat named the Chicken Pox. A week later, the Coast Guard suspended their search for the pair.

After he was questioned Tuesday, Nathan left the Coast Guard base with his father.

The Carman family has had hard times. In 2013, Linda Carman’s father was found shot to death in his Windsor, Connecticut home. That crime remains unsolved. According to WFSB, Nathan Carman was “a primary person of interest” in the murder of his grandfather.

Nathan 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.

A police affidavit issued to obtain the search warrant of the Vermont home “indicates that Linda and Nathan had different intentions as to the final destination of the fishing trip.”

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

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

Linda, it states, thought they were going 20 miles off shore. Nathan, according to people he spoke with before he left, had other plans to take them roughly 100 miles out. “I thought he said the canyons which are off Block Island,” said Mike Iozzi who struck up a casual conversation with Nathan hours before he left the dock.

“I didn’t see him with fishing poles,” Iozzi told WBZ-TV. “I didn’t even see him with food.”

The affidavit also stated that Nathan’s boat was in need of mechanical repair.

On Sunday, Nathan was found drifting in an inflatable raft by the Chinese freighter Orient Lucky, about 100 nautical miles south of Martha’s Vineyard.

There was no mayday call and no radio transmission of any kind from the fishing boat, according to the Coast Guard. On Tuesday, the Coast Guard released audio of their conversation with Nathan after he was rescued by the freighter.

READ MORE: Nor'easter Tosses Boats Ashore, Topples Press Box, Knocks Out Power To All Of Cohasset



“Mom and I, two people, myself and my mom were fishing on Block Canyon,” Nathan said. “There was a funny noise in the engine compartment, I looked and saw a lot of water.”

“I had my mom bring in the reel, I brought the safety stuff forward,” Nathan said. “I was bringing one of the safety bags forward and the boat stopped out under my feet. When I saw the life raft, I did not see my Mom. Have you found her?”

Coast Guard Search and Rescue Controller Richard Arsenault responded, “No, we haven’t been able to find her yet.”

Nathan Carman arrives at Coast Guard base in Boston (WBZ-TV)

Nathan Carman arrives at Coast Guard base in Boston (WBZ-TV)

Nathan told Arsenault that after he got to the life raft, he began whistling and calling and did not see his mom.

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

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

Coast Guard Petty Officer 3rd Class Nicole Groll said there are some lingering questions after an exhaustive search that failed to locate Nathan.

“He said his boat sunk off Block Canyon, and we scoured 62,000 nautical miles of sea,” she said. “He was found in the search area, his boat went down in the search area. Why didn’t he see us? Why didn’t we see him?”

“We want to know what we can do to make our search efforts better, so, god forbid there’s another person we’re searching for, we can do the very best we can to make sure that they’re found and brought home safely,” she added.

WBZ NewsRadio 1030’s Ben Parker reports

MORE NEWS: Roger Goodell's Excuse For Secrecy In Washington Investigation Is Preposterous And Insulting