His son was no insurgent, Dost said. He was walking home from prayers on the night of May 5 when he was shot and killed on a busy Kabul street by U.S. security contractors.
"The Americans must answer for my son's death," Dost said as a large crowd of young men murmured in approval.
The shooting deaths of Raheb Dost, 24, and another Afghan civilian by four gunmen with the company once known as Blackwater have turned an entire neighborhood against the U.S. presence here.
Already enraged by the deaths of civilians in U.S. military airstrikes, many Afghans are also demanding more accountability from security contractors who routinely block traffic and bark orders to motorists and pedestrians.
As the war escalates in Afghanistan and the U.S. seeks to win over a wary public, incidents such as the one that left Raheb Dost dead raise uneasy ghosts of the Iraq war. With more than 70,000 security contractors or guards in Afghanistan and billions of dollars at stake in lucrative government contracts, the consequences of misconduct are significant.
A June report by the Commission on Wartime Contracting in Iraq and Afghanistan cites serious deficiencies among private security companies in Afghanistan in training, performance, accountability and effective use-of-force rules.
The report says U.S. authorities in Afghanistan have not applied "lessons learned" in Iraq after a 2007 incident in which Blackwater guards shot and killed 17 Iraqi civilians in Baghdad. Iraq revoked the firm's license, and five contractors face U.S. federal manslaughter and weapons charges.
The Afghan Interior Ministry has stepped up licensing of security contractors and is demanding stricter monitoring. The ministry says it wants limits on the number of contractors here, even as the Pentagon considers hiring a private security firm to provide more guards for its military bases.
Members of parliament, responding to complaints from constituents, have proposed legislation cracking down on contractors.
"They have caused some serious difficulties for the people," said Fazlullah Mujadedi, a member of a parliamentary commission looking into security companies.
The extent of those difficulties is hard to gauge: The United Nations office in Kabul, the capital, didn't break out contractor involvement in its recent report on deaths or injuries of civilians, and other agencies here don't track such incidents.
In June, Afghan President Hamid Karzai accused Afghan guards working for U.S. forces of killing a police chief and four police officers in the southern city of Kandahar.
The U.S. military called it an "Afghan on Afghan incident" and said no U.S. forces were involved.
Such incidents have fed a sense among some Afghans that private gunmen are above the law -- both Afghan and American. Security contractors are subject to Afghan laws, but the four contractors in the May shooting left for the U.S. before Afghan authorities could mount a case against them.
Since February, oversight of security contractors in Afghanistan has been entrusted not to Congress or the Pentagon, but to a British-owned private contractor, Aegis. The company was hired by the American government after the U.S. military said it lacked the manpower and expertise to monitor security contractors. Aegis is supposed to help U.S. authorities make sure contractors are properly trained, armed and supervised.
The wartime contracting commission, set up by the U.S. last year, expressed concern over "limited U.S. government supervision" of private security contractors in Afghanistan. Many are unlicensed and unregulated, said Zemaray Bashary, an Interior Ministry official.
Anger toward hired gunmen runs especially high in Yaka Toot, a densely packed neighborhood in east Kabul, where residents are still simmering over the May shooting.
Residents say the U.S. contractors opened fire without provocation after one of their vehicles tipped over in a traffic accident. Killed along with Dost was Romal, 22, a passenger in a Toyota sedan on his way home from work. Like many Afghans, Romal used just one name.