With three rounds of pistol fire, President Hamid Karzai’s half brother was assassinated Tuesday morning in the city he dominated for years, opening a power vacuum that could destabilize Afghan politics in a region at the heart of the American war against the Taliban.

Ahmed Wali Karzai, the most powerful man in southern Afghanistan, was meeting with tribal elders and politicians in his heavily fortified home when longtime confidant Sardar Mohammad arrived with two weapons, one of them concealed, according to an account by a U.S. official.

Mohammad, a police commander, turned over one gun to a guard to appear unarmed, then told Karzai he had important information to share. As they entered a private room, he handed Karzai a piece of paper, the U.S. official said, and as he read it, Mohammad opened fire with the second pistol. Mohammad was then gunned down by Karzai’s guards.

The Taliban asserted responsibility for Karzai’s killing, and a U.S. official confirmed that the insurgent group may have influenced Mohammad, who had commanded checkpoints in the Karzai family’s ancestral village. But others were skeptical that insurgents were to blame: Karzai, the Kandahar provincial council chief, had become for many a symbol of the venality of Afghanistan’s new ruling elite, and he had a long list of enemies from his business and political dealings.

 The killing underscores the continued vulnerability of Afghan officials as the United States prepares to reduce its military presence, and likely will complicate U.S. efforts to bolster security in southern Afghanistan. Karzai, long dogged by allegations of corruption and involvement in the drug trade, recently had shown more willingness to work with the United States to defeat insurgents and strengthen local government.

“He was the number-one man in Kandahar,” said Mir Wali Khan, a former parliament member from Helmand province who was at Karzai’s house at the time of the shooting. “We expect now the security of Kandahar will get worse, and the fighting among the tribes will grow stronger and stronger.”

The killing shook Afghanistan’s political establishment, which had already been rattled by a string of assassinations of top government officials.

President Karzai learned of the news shortly before he appeared at a news conference with French President Nicolas Sarkozy.

“This morning, my younger brother, Ahmed Wali Karzai, was martyred at his home,” Karzai said with a strained voice. “This is the life of the people of Afghanistan, and each Afghan family has suffered in such a way.”

By late afternoon, President Karzai’s convoy of more than 20 SUVs roared onto the tarmac of Kabul’s airport for a flight to Kandahar, where a funeral was scheduled for Wednesday morning.

Ahmed Wali Karzai, a father of five children, was born to a prominent family in Kandahar in 1963 and studied economics at Kabul University before leaving Afghanistan after the Soviet invasion, relatives said. He lived in the Netherlands, then moved to Chicago, where he worked long hours at his brother’s restaurant and watched American and Indian films late into the night. In 1987, he moved to Wheaton to live with his father, then returned five years later to Pakistan. He contemplated — along with friends and family members — a return to Afghan political life, which became a reality after the overthrow of the Taliban in late 2001.

“Of all the Karzai brothers, he was the most politically talented,” said his brother Mahmoud Karzai, 57, who owns a residential housing division in Kandahar. “He had a way of getting along with people. He remembered everyone.”

But his political life in Kandahar was always tainted by allegations that he profited from the opium trade and oversaw a semi-legal business empire, accusations he always denied.

U.S. officials believed that Karzai had access to tens if not hundreds of millions of dollars through a slew of enterprises ranging from private security companies to trucking interests to the opium trade — businesses that never bore his name. He insisted that he owned none, and U.S. officials had difficulty proving malfeasance, to the point that the then U.S. commander in Afghanistan, Gen. Stanley A. McChrystal, instructed his officers last year to work with Karzai because they lacked proof against him.

For all the rumors of brutal behavior, Karzai often exuded a boisterous charisma. He spoke English with a Chicago accent and greeted his supplicants with a high-speed, foot-tapping energy, interrupting them every few minutes to field cellphone calls. Aspiring politicians, tribal chiefs and indigent farmers all filed into his house each day to seek his handouts or blessings or a ruling in a village dispute.

The home’s first floor often looked like an airport lounge, with dozens of Afghans sitting on the floor waiting for their audience in his second-floor carpeted meeting room, which was ringed with red couches and hung with rose-print drapes. In these meetings, he had the power to free prisoners or destroy political careers. 

To foreign visitors, he cast himself as a victim of political smears. He described himself as a misunderstood public servant — he once called himself the “Nancy Pelosi of Kandahar.” But he could not fully mask his bravado about the power and influence he could wield.

In the war against the Taliban, he was a valuable U.S. partner — and a paid CIA asset. He helped recruit a powerful paramilitary group known as the Kandahar Strike Force and served as a font of intelligence about insurgents. “Regardless of how you viewed the guy, [Karzai] deserves some of the credit for the rout of the insurgents in Kandahar,” said Bill Harris, a former senior U.S. civilian in Kandahar.

But Karzai’s influence, from his perch on the provincial council, also badly warped the province’s political institutions. His ostensible superior, provincial governor Toryalai Wesa, commanded a fraction of Karzai’s authority, despite the full force of American money and manpower backing Wesa up.

Karzai’s power earned him innumerable enemies. His Pashtun tribe, the Popalzai, seized top government jobs and the spoils of NATO’s contracting dollars, while other formerly powerful Kandahar tribes were pushed to the margins and many of their young men to the insurgency.

“Ahmed Wali had come to symbolize a pattern of public corruption, abuse of power and impunity,” said one U.S. official with considerable experience in Kandahar. “Now everything has changed. There is at least a possibility for more constructive local leadership to step up.

Mahmoud Karzai said he and his brother spoke at length Monday night about security in southern Afghanistan, hours before the targeted killing. “The Taliban is defeated. They cannot challenge the Afghan military,” Mahmoud Karzai recalled his brother saying. “All they can do is explode bombs and assassinate people.”

Sieff reported from Kabul. Staff writer Rajiv Chandrasekaran in Kandahar and special correspondents Javed Hamdard and Sayed Salahuddin in Kabul contributed to this report.