U.S. counterterrorism officials say a man removed Sunday from an Aeromexico flight in Montreal was the subject of a warning last week that Al-Shabaab terrorists might attempt to cross from Mexico into the United States.

Department of Homeland Security officials had requested that law enforcement in Houston be on the lookout for a suspected member of the Somali jihadist group. On Sunday, the flight from Paris to Mexico City was diverted to Montreal. Canadian authorities detained the man, identified as Abdirahman Ali Gaall.

U.S. counterterrorism officials told NBC News that Gaall is a Somali national with U.S. resident status. His wife is an American citizen. The Canada Border Services Agency confirmed that Gaall was on a U.S. no-fly list. More details on the case are expected to be made public at Gaall's deportation hearing scheduled for Wednesday.

FoxNews.com reported last week that the subject of the DHS warning was a Somali man named Mohamed Ali, who officials believe has ties to Al-Shabaab. Ali was thought to be in Mexico and preparing to illegally cross the border into Texas.

Another development that bears watching is the federal prosecution of Anthony Joseph Tracy, a Virginia man facing federal prosecution over his alleged role in a ring that illegally smuggled more than 260 Somalis into the United States. In an affidavit filed in U.S. District Court, Immigration and Customs Enforcement Special Agent Thomas K. Eyre wrote that Tracy admitted he was approached by al-Shabaab in Kenya but claimed that he refused to assist the group.

Tracy "said he helped 272 Somalis obtain fraudulent visas in Kenya between May 2009 and December 2009, at a rate of approximately five to ten Somalis a week," Eyre added.

Tracy "converted to Islam while in a U.S. prison in the 1990s and goes by the names Yusuf Tracy and Yusuf Noor." He admitted that working through the Cuban Embassy in Kenya, "he would help the aliens by providing and manufacturing fake documents that are required to obtain Cuban visas," Eyre wrote.

The Somalis allegedly smuggled into the United States by Tracy are reported to have scattered across the country and remain at large.