Relatives of a San Antonian killed in Afghanistan say the Marine Corps has withheld common knowledge that he died in a “friendly fire” incident.

“I feel I've been played a fool,” said Becky Whetstone, mother of Lance Cpl. Benjamin Whetstone Schmidt, who died Oct. 6 in Helmand province.

Whetstone said she was told Monday by a Wall Street Journal reporter who had embedded with her son's battalion that Schmidt was shot by a tank machine gunner who came up from behind during a firefight.

She said she posted the news on Facebook and immediately heard from individual Marines who unofficially corroborated the account.

“It was very fortunate that his whole platoon wasn't killed,” said Whetstone, a former San Antonio Express-News features columnist.

She and her brother and sister said the Marines held back details that should have been shared with the family.

“All at once, we find out from another source,” said her brother, Bud Whetstone, of Little Rock, Ark.

Schmidt's father, Dr. David Schmidt, team physician for the Spurs, also has said he learned from unofficial sources that his son died from misdirected fire. Unlike his ex-wife, he hasn't criticized the Marines' dealings with the family.

Marine Corps officials at the Pentagon and at Camp Pendleton, Calif., where Schmidt's battalion was based, had no comment Tuesday. One official in Washington, speaking anonymously, said an investigation into the death is “probably a number of weeks” from completion.

Schmidt's aunt, Martha Whetstone, said the handling of the incident was not as egregious as in the 2004 death of Army Cpl. Pat Tillman but is disturbing because a “material fact” has been completely withheld from the family.

“They put a muzzle on the people who did know,” said the aunt, who is heavily involved in government and politics in the San Francisco area.

In Tillman's death, the Army first said his unit had been ambushed in Afghanistan. Family members said they were not told for weeks that he'd been killed by “friendly fire,” though the Army had known prior to his burial. Although some soldiers were removed from the Army Rangers for tampering with evidence, Tillman's family has alleged that Army commanders also were part of a cover-up.

At the time Schmidt was buried, Oct. 14, his family had been told unofficially by Marines who saw the incident that he'd been killed by an enemy combatant. Other Marines made vague references that there were widespread rumors.

Becky Whetstone said the Marines should have told immediate relatives that the death was believed to be accidental, so relatives could process their loss knowing the best available information.

“I was already feeling anguish. Now it feels exponential compared to what it was before,” she said.