Lawyers for a Sudbury man urged a federal Appeals Court on Tuesday to overturn his 2012 convictions for conspiring to kill American soldiers and for supporting Al Qaeda, arguing that the evidence brought by prosecutors was of such a volume and inflammatory nature that it prejudiced the jury.
“The purpose of the evidence was to frighten the jury, and it worked,” attorney Sabin Willett said in his oral argument, made before more than 50 family members and supporters of Tarek Mehanna at the John Joseph Moakley US Courthouse in South Boston.
In a closely watched trial last year, Mehanna, 29, was sentenced to 17½ years in federal prison following his conviction on seven counts of conspiring to provide materials to support terrorists, conspiring to kill in a foreign country, and lying to authorities in a terrorism investigation.
“It was hard for me to come back to this [court] room again and see their [the prosecutors’] faces,” Souad Mehanna said after the hearing. “My son is innocent, and they’re still locking him away from me.”
But after a three-judge panel of the Court of Appeals for the First Circuit grilled federal prosecutors about the legal underpinnings and evidence in the case, Souad said she was slightly hopeful.
“We can’t wait for him to come out and live his life, for all of us to live our lives. . . . If we don’t win this time, we will keep fighting.”
The Appeals Court said it will take the matter under advisement and rule at a later date.
Prosecutors said Mehanna’s trip to Yemen in 2004 was the failed attempt of a young radical to join a terrorist training camp to carry out jihad, or holy war, against US soldiers in Iraq. Upon his return, they said, he used his knowledge of Arabic to translate and distribute Al Qaeda-promoted documents on the Internet.
But the defense argued Tuesday that Mehanna had only expressed his views, which he had a constitutional right to do, and that evidence concerning his time in Yemen and his translation activities was insufficient to link him to Al Qaeda.
“Our view is that if the government cannot tie the knot between Mehanna and Al Qaeda, this is simply speech, just protected opinion,” Willett said after the hearing.
US Attorney Carmen M. Ortiz’s office urged the three-judge panel to leave Mehanna’s convictions intact.
Assistant US Attorney Elizabeth Collery said the evidence told them “what his beliefs originally were, how he talked about them with other people, and [how he] recruited others to his cause.”
During Mehanna’s trial, FBI agents testified about videos of suicide bombings and the Sept. 11, 2001, terrorist attacks that were found on Mehanna’s computer, following a secret search of his Sudbury home in 2006.
Willett argued, however, that the evidence, which included “28 images of the World Trade Center in flames, 33 video clips . . . and thousands of posts,” was excessive.
The question at hand, Judge Bruce M. Selya said at the hearing, “is if the government grossly overdid it; put in so much evidence of such an inflammatory nature that they did it with a design to prejudice the jury.”
“Terrorism sparks emotions in all of us,” he said.
“This is a hard case,” he said at the end of Tuesday’s arguments. “It’s one of those cases that could bring bad lore on good judges. . . . We will try to be very careful.”
That remark, Willett said, was an unusual one.
“For Judge Selya to think it’s a hard case, that’s unlike most criminal appeals,” he said, explaining that such convictions are usually affirmed. “To hear that is encouraging.”
“I felt the judges gave more depth of consideration than what we saw from the trial jury,” echoed Mehanna’s younger brother Tamer after the hearing. “We are hopeful.”Alyssa A. Botelho can be reached at alyssa.botelho@
globe.com. Follow her on Twitter at @AlyssaABotelho.