The agency on Wednesday announced a $50,000 reward for information leading to the arrest of Ahmad Abousamra, 31, a dual US/Syrian citizen from Mansfield, who left the United States in 2006 and is thought to be living in Syria.
"Knowing that the public is the FBI's best ally in finding fugitives, today we're requesting your assistance to locate Abousamra," said Richard DesLauriers, special agent in charge of the FBI's Boston office.
The FBI said Abousamra is an associate of Tarek Mehanna, another Massachusetts resident, who was sentenced in April to 17-1/2 years in prison on several terrorism charges, including "providing material support to terrorists" and conspiracy to kill in a foreign country.
Abousamra, who has a degree related to computer technology and is fluent in English and Arabic, was charged in 2009 with conspiracy to provide material support or resources to al Qaeda.
The charges include taking multiple trips to Pakistan and Yemen in 2002 and 2004 to seek jihad training. He also allegedly traveled to Iraq with the hope of joining forces fighting against Americans overseas.
The FBI said that one of Abousamra's distinguishing characteristics is his "higher-pitched voice."
The agency is blanketing traditional and social media in its efforts to find Abousamra. "Wanted" posters will be issued in English, French and Arabic. The FBI will also buy what it termed "limited advertising on a social media site" to reach an overseas audience.