O'Hair was America's best-known atheist. In the 1960s, she took part in successful court battles to ban prayer and Bible-reading in U.S. public schools. She called herself the most hated woman in America.
Forensic scientists used medical and dental records to identify the remains of O'Hair, 76, her son Jon Garth Murray, 40, and Robin Murray O'Hair, 30, her granddaughter.
A stainless-steel artificial hip that was pulled from the ground was among the evidence used to identify the elder O'Hair, who had hip replacement surgery in 1988.
"This certainly gives us some closure," Roderick Beverly, agent in charge of the FBI's San Antonio office.
The family disappeared from San Antonio in 1995 along with $500,000 in gold coins. Investigators believe they were kidnapped, robbed and killed, and their bodies were cut up and dumped on a ranch near Camp Wood, about 125 miles (200 kilometers) from San Antonio.
Of the four suspects believed to have taken part in the plot, one is dead, allegedly at the hand of his partners, and three others have been convicted of various charges, including extortion. None of them has been convicted of kidnapping, and no murder charges have been filed.
The cause of death could not be determined with certainly for any of the victims, though Jon Murray appeared to have suffered a blow to the head. And a plastic bag found over his skull suggested he might also have been suffocated, said David Glassman, chairman of anthropology at Southwest Texas State University, who worked on identifying the remains.
When the ailing O'Hair disappeared, some speculated at first that she had gone off somewhere to die so that Christians would not pray over her.
It was David Roland Waters, O'Hair's former office manager, who led authorities to the grave. Waters, 53, struck a plea bargain and is scheduled to be sentenced March 30 on federal conspiracy charges.
Authorities also found a skull and hands of a fourth person, believed to be Danny Fry, one of the suspects in the family's disappearance. Fry's headless, handless corpse was found in 1995.
Glassman said he is waiting for dental records to identify the skull, which had holes in it along with traces of metal, suggesting the victim had been shot.
The examination could not determine if any of the victims had been tortured, or what was used to dismember them, Glassman said.
O'Hair's estranged son, William Murray, said the remains will be turned over to him for burial. William Murray was the subject of O'Hair's landmark lawsuit on school prayer but is now a Christian evangelist.
He said the victims will get a private funeral, but he will not pray for their souls.
"You cannot pray them out of hell," Murray said.