The parents of Pat Tillman, who died by "friendly fire" in Afghanistan in April 2004, already have accused US authorities of initially trying to cover up the circumstances of their son's death.
But Mr Tillman's brother, Kevin, who also served in Iraq and Afghanistan along with his brother, spoke out for the first time last week with an angry condemnation of the rationale for the Iraq war and Mr Bush's leadership.
"Somehow the more soldiers that die, the more legitimate the illegal invasion becomes," Kevin Tillman wrote in an essay published by Truthdig.com, a left-leaning website.
"Somehow torture is tolerated. Somehow lying is tolerated. Somehow reason is being discarded for faith, dogma and nonsense.
"Somehow American leadership managed to create a more dangerous world," wrote Mr Tillman, who gave up his own fledgling career in professional baseball to join the army.
Entitling his essay "After Pat's Birthday", Mr Tillman notes that US elections will be held on November 7, a day after his late brother's birthday, and calls for voters to hold Bush's Republican party accountable.
"Luckily this country is still a democracy. People still have a voice. People still can take action. It can start after Pat's birthday," he wrote.
His words have coincided with escalating violence in Iraq and generated bitter debate on the internet, with opponents and defenders of the war arguing over the meaning of Mr Tillman's death and the justification for the US invasion of Iraq.
Both the right and the left in American politics have battled to define Pat Tillman as a symbol, with conservative commentators questioning the veracity of reports that the former defensive back had opposed the Iraq war and Bush.
In the wake of the attacks of September 11, 2001, Pat Tillman was held up as a model citizen for choosing to give up a $US3.6 million ($A4.8 million) contract extension with the Arizona
Cardinals and instead enlist for military service.
The square-jawed, muscular athlete known for his tenacious play had avoided all publicity while in uniform and eventually made it into the elite Army Rangers.
His death near Afghanistan's border with Pakistan received elaborate media coverage, with his funeral carried live on the ESPN sports television network.
The US military first described how Pat Tillman had died in a hillside firefight with Taliban forces, and awarded him the Silver Star for valour.
Military officials later said Tillman had been killed accidentally by friendly fire in a chaotic engagement with the enemy. But eventually the Pentagon acknowledged that there was no hostile force involved, only gunfire from his fellow US Army Rangers.
Newspaper reports have alleged a possible cover-up and that the military knew early on that Tillman had been killed by friendly fire but kept quiet until after the funeral was held.
In March, the defence department launched a criminal probe into the case, the fifth successive investigation, which is still pending.
Critics of Bush have seized on Tillman's story saying it illustrates the White House's preference for propaganda and public relations spin.
"Though Tillman himself was so idealistic that he refused publicity of any kind when in the Army, he was exploited by the war's cheerleaders as a recruitment lure and was needed to continue in that role after his death," wrote New York Times columnist Frank Rich.
The Truthdig.com website that ran Kevin Tillman's essay has been overwhelmed with responses, including some from veterans who attacked the author for his strident views.
"I too have served and I too have lost! Some of us chose to be bitter, some of us chose to move on!" read one entry.
"Tillman's death, while tragic and unfortunate, does not reflect the views of all military personnel, a lot of whom have seen hell, seen the affects (sic) of Saddam's power and greed, and viewed directly what the axis of evil can do to a country," said another entry.
Pat Tillman's father, Patrick, has alleged the Pentagon tried to hide the truth about his son's death.
"I think they thought they could control it, and they realised that their recruiting efforts were going to go to hell in a handbasket if the truth about his death got out," he told the Washington Post.
"They blew up their poster boy."