Irfan Khan, a Pakistani immigrant, was trying to live the American dream as he drove a Miami taxicab to support his family while dabbling in real estate and studying computer programming.

But the FBI and prosecutors branded him as a “sympathizer” of the Pakistani Taliban who plotted with his father, a Muslim cleric, and siblings to raise money for the terrorist organization.

Khan, a 39-year-old naturalized U.S. citizen, was facing a fall trial. If convicted, he was looking at up to 15 years in prison.

But last week, without explanation, the U.S. attorney’s office in Miami decided to drop all charges against Khan, who had been detained for nearly a year before finally obtaining bail in April.

“They realized it was all nothing, and that’s why the case was dropped,” said Shabbir Khan, who owns a Hialeah taxi repair business and helped his friend post a bond. “He called me and said he was very happy. He thanked God that the truth came out, and thanked us for our support.”

Miami interim Federal Public Defender Michael Caruso said his client was relieved by the dismissal of his case, and grateful for the support of family, friends and the South Florida Muslim community throughout the ordeal.

Asked why he thought prosecutors dropped the terrorism charges, Caruso said: “I can’t speak to the government’s reason for dismissing the case, but Irfan was completely innocent of the charges brought against him.”

FBI agents arrested Khan in the wee hours of May 14, 2011, in Los Angeles. He had been working on a computer programming project for a Southern California corporation, while flying back to Miami-Dade on occasion to be with his wife and two children.

An indictment charged Irfan Khan; his father, Hafiz Khan, 77, the former leader of a Miami mosque; his brother, Izhar Khan, 25, the one-time head of a Margate mosque; and three others with conspiring to collect and send at least $50,000 from South Florida to the Taliban between 2008 and 2010.

The other defendants — all believed to be living in Pakistan — are Irfan Khan’s sister, Amina Khan; her son, Alam Zeb; and Ali Rehman.

The Taliban, a U.S.-designated terrorist organization, has been accused of carrying out violent attacks against American and Pakistani interests. It has been linked to al-Qaida, and is suspected of playing a role in the failed May 2010 attempt to bomb New York’s Times Square.

The FBI used a confidential informant, bank transfer records and more than 1,000 wiretapped phone calls to build the case, which drew national media attention.

“They used the money to provide guns and support to the Taliban and their families,” U.S. Attorney Wifredo Ferrer said at a weekend press conference on the day of the arrests.

For his part, Irfan Khan was accused of making four wire transfers — for $990, $980, $980 and $500 — to Pakistan, including three to a Taliban commander and one to his sister, according to court records and an indictment that charged him with conspiring to provide financial support to the Taliban.

He was also accused of talking with his father, a former imam of the Flagler Mosque in west Miami-Dade, about supporting acts of violence in the Swat Valley of Pakistan, a hotbed of Taliban militancy.

“This defendant, Irfan Khan, speaks of violent incidents that occur in Pakistan,” federal prosecutor Sivashree Sundaram told U.S. District Judge Adalberto Jordan during a detention hearing last July. “He expresses his distaste for the Pakistani government. He advocates victories by the Pakistani Taliban, and then he backs all of this up by providing material support and conspiring to provide material support to that very violent terrorist organization.”