The Los Angeles Times reported Sunday that Dele's brother, Miles Dabord, is "living only through artificial means," according to his mother. Dabord was found unconscious Sept. 14 in Tijuana, Mexico, and hospitalized in suburban San Diego. He has been in a coma since, and the FBI only learned his identity Thursday.
Dabord remained in critical condition Monday morning at Scripps Memorial Hospital in Chula Vista, Calif. said hospital spokeswoman Monica Montano.
The Times reported that Dabord's mother, Patricia Phillips, said doctors discovered severe damage to her son's brain as a result of an insulin overdose and failure to take his asthma medication.
Investigators in Tahiti hope to gain clues about where Dele and two others aboard a catamaran vanished in July by studying a satellite phone aboard the sailboat. Calls made from the phone could help authorities map their coordinates, a French official in the investigation said, speaking on condition of anonymity.
Phillips told the newspaper the decision on whether to remove Dabord from life support was "inevitable," and that she plans to meet with a neurologist Monday to assess her son's brain damage.
The FBI arrested Dabord on suspicion of impersonating his younger brother while trying to buy $152,000 in gold in Phoenix.
Phillips had told the Times she fears her son may have tried to commit suicide because he was overcome with guilt, believing he was responsible for his brother's disappearance.
Investigators in Tahiti believe Dabord killed Dele, Dele's girlfriend and the French captain on board Dele's sailboat. Dele, his girlfriend Serena Karlan and the skipper, Bertrand Saldo, haven't been seen since July 8.
A team of FBI-led investigators found what they believe are bloodstains on the catamaran, which Dabord docked at a Tahitian port July 18 before departing the French territory.
Phillips told The New York Times, in a story published Sunday, that she received a phone call from her son earlier this month, during which he was crying and told her: "I found something and I tried to cover it up, but I didn't do what they're saying. No one will believe me."
On Friday, Phillips was at her son's bedside. "I wanted to hug him, to stroke his face, to hold his hand," she said.
The FBI agents began departing Tahiti on Sunday, the French official said. He declined to say whether all 13 agents had left.
Investigators were still interviewing witnesses and were evaluating whether to dismantle part of the catamaran to search for more clues.
Dele changed his name from Brian Williams during an NBA career in which he played for several teams, including the Chicago Bulls' 1996-97 championship team. The free-spirited center walked away from a $35 million contract with the Detroit Pistons in 1999.
Dabord was traveling with Dele and his party on a trip from New Zealand to Hawaii when they stopped at an island near Tahiti.