FREMONT, Calif. — The banging on the door jolted Sal Shafi awake. F.B.I. agents were looking for his son. “Where’s Adam?” they yelled. “Where’s Adam?”
Terrified, Mr. Shafi led the agents, guns drawn, up the stairs toward his son’s bedroom. He watched as they led his 22-year-old son away in handcuffs, backed by evidence of Adam Shafi’s terrorist ambitions.