Tarek Mehanna, 29, of Sudbury, faced four terror-related charges and three charges of lying to authorities. A federal jury found him guilty of all counts after deliberating for about 10 hours.
Prosecutors said Mehanna and two friends conspired to travel to Yemen so they could receive training at a terrorism camp and eventually go on to Iraq to fight and kill U.S. soldiers there.
When the men were unable to find such a training camp, Mehanna returned home and began to see himself as part of the Al Qaeda "media wing," translating materials promoting violent jihad and distributing them over the Internet, prosecutors said.
Mehanna, who was born in the U.S. and raised in the Boston suburbs, will be sentenced April 12 and could be sent to prison for the rest of his life. His mother, Souad Mehanna, sobbed after the verdict was read and was consoled by her younger son, Tamer. Mehanna's lawyers also wept.
Mehanna's father, Ahmed, a professor at the Massachusetts College of Pharmacy and Health Sciences, said he was stunned by the verdict.
"I can't even think," he said. "It was political."
Mehanna attorney J.W. Carney Jr. said the defense team will appeal. He said he was upset with the verdict and what he called the extraordinary leeway prosecutors had to present evidence the defense considered prejudicial, including references to Al Qaeda and the Sept. 11 attacks.
"The charges scare people. The charges scared us," Carney said. "The more that we looked at the evidence, the more we got to know our client, Tarek, the more we believed in his innocence."
U.S. Attorney Carmen Ortiz disputed that the prosecution's evidence was inflammatory.
"The heart of the case is really this: Did Mr. Mehanna conspire to support terrorists, conspire to kill in a foreign country and then did he lie to federal investigators?" she said. "Today a jury of his peers concluded that he did that."
During the trial, which started in October, Mehanna's attorneys portrayed him as an aspiring scholar of Islam who traveled to Yemen to look for religious schools, not to get terrorist training. They said his translation and distribution of controversial publications was free speech protected by the First Amendment.
Prosecutors focused on hundreds of online chats on Mehanna's computer in which they said he and his friends talked about their desire to participate in jihad, or holy war. Several of those friends were called by prosecutors to testify against Mehanna, including one man who said he, Mehanna and a third friend tried to get terrorism training in Yemen so they could fight American soldiers in Iraq.
Mehanna's lawyers told jurors that prosecutors were using scare tactics by portraying Mehanna as a would-be terrorist and were trying to punish him for his beliefs.
The defense built its case on the testimony of a half dozen terrorism experts. Mehanna did not testify.
His lawyers acknowledged that Mehanna expressed admiration for Osama bin Laden, but said he disagreed with bin Laden and other Al Qaeda leaders about many things, including the use of suicide bombers and the killing of civilians.
Jurors began deliberating Friday. In his instructions, U.S. District Judge George O'Toole Jr. told them that in order to find Mehanna guilty of conspiracy to provide material support to Al Qaeda, they must find that he worked "in coordination with or at the direction of" the terrorist organization. He said independent advocacy on behalf of the organization was not a violation of the law.