When 20-year-old Hamid Hayat left his home in California a little more than two years ago, he was like a lot of young Americans--aimless and a bit unsure about his future. Rail-thin and addicted to videogames, he lived with his parents in Lodi, Calif., a small farming town south of Sacramento. An amiable ice-cream vendor, his father, Umer Hayat, was known around the neighborhood as Homer, after the "Simpsons" sticker on the back of his truck. But the younger Hayat had trouble finding steady work. So when his mother fell ill with liver disease in 2003, the family traveled back to their native Pakistan, where they sought both treatment for her and a wife for young Hamid. He was no stranger to Pakistan. Though born in California, he'd spent his teen years in Behboodi and Rawalpindi, living with relatives and attending religious schools. Returning to Pakistan as an adult, he struck some relatives there as adrift. He whiled away hours a day watching movies on TV or vegging in front of his PlayStation 2. "He didn't know what he wanted to do with his life," his cousin Usama Ismail told NEWSWEEK.

Last week federal prosecutors said that Hayat knew exactly what he wanted to do: launch murderous terrorist attacks against Americans. Just days after Hayat returned to the United States last month, he and his father were detained by the FBI--the first arrests in what officials called a long-running investigation into a suspected terror network in the area. Court documents allege that Hamid Hayat spent part of his time in Pakistan at a secret Qaeda-backed training camp where recruits pinned up pictures of George W. Bush for target practice. Terrorism charges have not been brought against the Hayats. Instead, both men are accused of making false statements about the training camps when they were first questioned by federal agents. Upon further questioning, the Feds say, Hamid Hayat eventually gave a detailed account of his time in the camp. Lawyers for both men said they did not believe their clients were involved in any terrorist activity (the Feds have until June 21 to bring formal charges). Hamid's cousin Ismail laughs at the idea of his relative planning a terror strike. "This guy didn't know how to build anything," he says. "Any time something broke, he would call me to fix it."

The arrest of the Hayats, followed the next day with the arrests of two local imams on immigration charges, was portrayed by the FBI as a demonstration of how far the bureau's efforts to thwart domestic terror have come since September 11. It didn't hurt that the success was announced the same week that the Justice Department released a damning report detailing the FBI's failed attempts to catch the 9/11 hijackers. The FBI clearly hopes the Hayat case will help reassure the public that things at the bureau have changed.

Yet last week there were already questions about how strong the case against Hamid Hayat really is, especially after the Justice Department mistakenly released a draft of the affidavit in the case, only to change it a few hours later. The original document contained alarming allegations: that Hayat had admitted that "hundreds of attendees" from around the world had been at the camp, and that he had been trained to attack "hospitals and large food stores" in the United States. In the new affidavit presented at a press conference last Wednesday, those details had been removed. FBI Special Agent John Cauthen says the reference to "hundreds of attendees" was not deemed to be "relevant" to the Feds' case. As for the hospitals and food stores, Cauthen says the agent who interviewed the younger Hayat wasn't "comfortable" that there was any "specific threat" against such targets.

Despite the early snafus, the case against Hayat cannot be easily dismissed. FBI officials said the probe began two years ago with suspicions about a radical presence in the Islamic community around Lodi. One former law-enforcement official, who asked not be identified because the case is still underway, said the Lodi probe was an early test of the FBI's post-9/11 focus on suspected radical mosques--a practice that caused controversy three years ago, when federal agents were given more leeway to work undercover in religious institutions.

But the case took on new urgency at the end of last month, when Hamid Hayat, now 22, decided to return home from Pakistan. According to his cousin Ismail, Hayat had married and wanted to raise a family back in California. Hayat apparently didn't know that his name had been placed on the U.S. government's "no-fly list." Federal officials wouldn't explain how Hayat's name got there, but family ties may have played a part. Hayat's grandfather, Qazi Saeed Ur Rehman, runs a madrassa in Rawalpindi and, according to the FBI affidavit, is a "close personal friend" of the man who ran the jihadist camp the younger Hayat allegedly attended.

When Hayat stepped aboard a flight from South Korea to San Francisco on May 29, his presence on the no-fly list alerted U.S. law enforcement. The plane was diverted to Japan, where Hayat was questioned by FBI agents. According to the affidavit, Hayat denied any connection to terrorism. The agents downgraded him to a less-restrictive "selectee list," which would flag Homeland Security to search and question him every time he entered the country. When he got home, Hayat agreed to another interview. He also consented to a polygraph test, which the Feds say he flunked. After two more hours of questioning, Hayat allegedly broke down and confessed. He admitted spending six months at a Qaeda-backed jihadi training camp where "he and others at the camp were being trained on how to kill Americans," according to the affidavit released last week. Hayat, who said that he "specifically requested to come back to the United States to carry out his jihadi mission," described the camp as providing "structured paramilitary training" in weapons, explosives and hand-to-hand combat, according to the affidavit. Hayat's father, who had denied that his son had any terror ties, also changed his story after being shown a videotape of his son's confession, the authorities allege. He admitted financing his son's trip to Pakistan--and sending him a $100-a-month allowance.

For now, the Hayats sit in a California jail. The FBI knows that the case--and the bureau's credibility--will be under scrutiny. Since 9/11, the FBI has chased "an incredible number of allegations," says Dennis Lormel, a senior FBI counterterrorism official until December 2003. Yet Lormel says he's "not aware of any specific [Qaeda] cells" that have been found--only individual operatives. Now it's up to the Feds to prove that Hamid Hayat was a would-be Qaeda killer, and not just another unwitting bumbler tangled in the dragnet.