David Corneau, whose pregnant wife was ordered into custody because she refused to have a medical examination, had been jailed since June.
Prosecutors say they have evidence Corneau's infant son, Jeremiah, died minutes after being born because he did not receive medical attention. Another sect member's child, 10-month-old Samuel Robidoux, allegedly starved to death after he stopped nursing, but prosecutors say he was developing normally until the group stopped feeding him.
Investigators suspect the sect members buried the two dead children in Baxter State Park in Maine. The bodies have not been found.
Members of the small fundamentalist Christian sect reject the legal system, organized religion, banking, science, and medicine. Their total refusal to cooperate with the grand jury investigation landed eight of them, including Corneau, in jail for contempt of court.
Corneau's attorney, Robert George, said the goal of having his client assert his Fifth Amendment right not to incriminate himself was to get him out of jail. "He would not say this is acknowledging the legal system. He would say he's just protecting himself and his family," George said.
Prosecutor Ron Moynihan said Corneau was the first sect member to hire a lawyer. "I consider this a positive development today. We're always hopeful," Moynihan said.
On Aug. 31, a judge ordered Corneau's pregnant wife, Rebecca, held at a medical facility for pregnant inmates for the safety of her unborn child. She had refused to undergo medical examinations.
The sect consists of about two dozen adults and children from related families in Attleboro, near the Rhode Island state line in southeastern Massachusetts.