Washington CNN  — 

The FBI on Thursday arrested an Iraqi-born American citizen in Texas, alleging he traveled to Syria to fight with ISIS terrorists and returned to the U.S.

The case against Bilal Abood is one indication of federal counterterrorism officials’ new stance on terrorism cases in light of the recent foiled terrorist attack in Garland, Texas, against a Mohammed cartoon contest event.

Prosecutors charged Abood with lying to the FBI, but the case represents much more. Abood is one of hundreds of people the FBI is monitoring in some way, many of whom investigators suspect could be motivated to carry out attacks but though the evidence remains difficult to assemble.

Abood, who formerly worked as an interpreter for the U.S. Army in Iraq, migrated to the U.S. in 2009.

The FBI alleges that agents stopped Abood as he tried to travel in 2013, when he claimed he was planning to visit family in Iraq.

He later told the FBI in an interview in 2013 that he actually was planning to travel to Syria to fight with the Free Syrian Army, a rebel faction fighting the Assad regime that has in the past enjoyed some U.S. support.

Abood later left the U.S. for Turkey via Mexico, the FBI alleges.

He returned months later and claimed to the FBI that he had been fighting with the FSA.

The FBI seized his computers in July 2014 and found that Abood had pledged an oath to the leader of ISIS, Abu Bakr al-Baghdadi.

According to the FBI, Abood in June 2014 posted on Twitter a message saying: “I pledge obedience to the Caliphate Abu Bakr al-Baghdadi. Here we renew our pledge to the Caliphate Abu Bakr al-Baghdadi.”

The FBI says Abood spent time watching propaganda videos of ISIS atrocities, including beheadings.

One of the men who carried out the Garland attack, Elton Simpson, was under FBI investigation after posting extremist messages on Twitter and making contact with an ISIS recruiter in Syria. The FBI did not know that he was plotting an attack or that he had traveled to Texas, though agents were aware he had expressed interest in the Mohammed cartoon contest event.

In light of the Garland attack, FBI Director James Comey ordered counterterrorism investigators last week to reassess cases of people who the FBI was already tracking to determine whether more action was necessary against suspects. One law enforcement official likened it to trying to “shake the trees more aggressively.”

The Abood case was already in an advanced state of investigation, law enforcement officials say. But counterterrorism officials say it represents an example of moving more quickly to take possible threats off the streets, instead of waiting longer to monitor and build an investigation against suspects.