Nuradin Abdi was convicted in 2007 of planning to blow up an Ohio shopping mall.
Iyman Faris was convicted in 2003 of planning to blow up the Brooklyn Bridge.
Christopher Paul was convicted in 2008 of conspiring to use explosives against targets in the U.S. and Europe.
All three terrorists worshiped and socialized at a small mosque in Columbus, Ohio, and, according to David B. Smith, an attorney for Faris, were part of a larger group of jihadists and extremists who frequented the mosque.
The FBI now is investigating reports of links to that same mosque by Muslim-convert Abdulhakim Muhammad who allegedly shot and killed one soldier Monday and critically wounded another in a drive-by attack on a Little Rock, Ark., recruiting station, ABC News has learned.
According to law enforcement sources, they have received reports that Muhammad appears to have attended the mosque during a period from 2006 to 2007 when evidence indicates he resided in Columbus. It is unclear what, if any, links he had to the individuals already convicted.
However, his possible links to the mosque are one promising avenue under investigation as the government attempts to reconstruct Muhammad's path to radicalization and to establish firmly whether he acted alone in the recruiting station shooting.
The mosque, according to well informed sources, is a small house of worship that has regularly been frequented by foreigners with radical sympathies who, after their stops in Ohio, continued onward. The Imam of the mosque was not immediately available for comment.
Columbus has been identified as the jumping off point for Somalis residing in the United States, including Somali Americans, to become radicalized and then head overseas to wage jihad.
Muhammad most recently had come to the attention of law enforcement authorities following his arrest in Yemen last year while carrying a forged Somali passport.
Muhammad, 24, was the subject of a preliminary investigation by the FBI's Joint Terrorist Task Force and may have also been the subject of a prior investigation by authorities in Columbus, Ohio.
Muhammad's Travels to Yemen Scrutinized
His travels to Yemen are another promising area of investigation by the FBI and to other intelligence agencies. While in Yemen it is believed that Muhammad attended the Damaj Institute, an Islamic institute attended by a number of radicalized U.S. converts, which was once attended by John Walker Lindh, the "American Taliban" captured in Afghanistan.
It is unknown what role Muhammad's visit to Yemen may have played in his radicalization. His lawyer Jim Hensley told the Associated Press today that Muhammad went to Yemen to teach English to Afghan war refugees, but was jailed over problems with his visa.
Hensley said Muhammad was "tortured" and "radicalized" while in the Yemeni prison.
Prior to his drive-by shooting at the Little Rock recruiting center, Muhammad had used the Google Maps application to investigate recruiting centers in at least five other states, as well as Jewish institutions, a day care center, a post office and a Baptist Church, according to a report issued Tuesday by the Department of Homeland Security, ABC News has learned.
Recruiting centers in New York, Atlanta, Louisville and Philadelphia were on a list of possible targets, based on evidence found in Muhammad's home, according to the report.
A not-for-profit group the Secure Community Network, which is known to be reliable when concerned with threats to parts of the U.S. Jewish community, expanded on the government report.
"Muhammad may have considered and conducted research on other targets in addition to the military recruiting center in Little Rock, including military sites, government facilities, as well as Jewish institutions in several cities throughout the United States," SCN, a Jewish Federations of North America initiative, reported. "Law enforcement officials have reported that Muhammad may have researched Jewish entities in Little Rock."
Muhammad, upon his arrest Monday shortly after the fatal shooting, allegedly confessed and told authorities he acted alone, according to court documents.
Officials say that the FBI and the CIA are engaged in an intense effort to reconstruct Muhammad's path to extremism, taking apart his life, examining his friendships, educational records, travel within the United States and possible contacts with extremists overseas.
FBI Tries to Determine Whether Little Rock Shooter Acted Alone
Though police told ABC News that a preliminary investigation indicated that Muhammad acted alone, federal authorities also are trying to determine whether others were involved in any way -- including supplying weapons, lending encouragement or support, and helping to identify a target. Although he allegedly confessed, Muhammad also has pleaded not guilty to the shooting.