Mohammed Yusef Mullawala wanted a license to transport hazardous materials and to learn how to drive commercial tractor trailers. There was nothing unusual about that, until he told his teacher that he only wanted to learn how to drive forward, and he wanted to learn fast.

That was enough to raise a red flag with Darleen Crawford, president of the Nationwide Tractor Trailer Driving School in Smithfield, R.I., where Mullawala took driving classes.

Federal and state authorities are investigating why Mullawala was seeking a commercial trucking license after his behavior raised flags at the Rhode Island driving school. Crawford said he was also insistent on taking the test necessary to earn a license to transport hazardous materials.

Mullawala, a 28-year-old citizen of India who is of Pakistani descent, is now in federal custody in Massachusetts on immigration violation charges.

"We are still digging into his background, digging into where he lived in Rhode Island, New York and New Jersey," Major Steven O'Donnell with the Rhode Island State Police told FOXNews.com on Wednesday. "A lot of still doesn't make any sense, why he would be doing what he was doing."

Crawford said Mullawala came to the school with a Rhode Island driver's license inquiring how to obtain a commercial driver's license within a month. It normally takes around eight weeks for a student to go through all of the required courses before he or she obtains a permit, she said.

"We've been doing this for quite a long time and a lot of things just didn't add up," Crawford said.

Crawford started documenting suspicious activity: Mullawala lived in New York City but traveled to Rhode Island for the driving classes; he missed his first day of classes; and he was very insistent on getting his hazardous material transport license.

But the fact that he only seemed interested in driving forward was the most concerning.

"We tell them from Day One, 'you will be backing up,' 'you'll be backing up every single day,'" Crawford said, adding that it normally takes two to three weeks of practice backing up before drivers get road permits and learn how to drive forward, among other things.

The situation was reminiscent of when some of the Sept. 11, 2001, hijackers told their flight-school instructor they were only interested in how to fly planes at certain altitudes, not so much how to land or take off.

"He was just really pushing to get out of here," Crawford said. "I've been doing this for 30 years so you just sort of know when something doesn't feel right."

After Mullawala took two classes, Crawford contacted Highway Watch, which had conducted an anti-terrorism and safety program at her school.

Jim Sutton, director of the Highway Watch's Information Sharing and Analysis Center, said it was the "calibrated judgment" of his five-person staff of former military, national intelligence and security officers that caused them to pass Mullawala's information on to federal authorities.

"Over a period of time, you learn that certain indicators are very valid, that they just stand out," Sutton said. "They're so anomalous to the norm that you say to yourself, 'there is something here. We need to pursue, we need to follow up.'"

In Mullawala's case, Sutton said, "there was a sense of urgency he had in finishing the course."

"Well, you don't learn those type of mechanical skills very fast," he added.

The ISAC contacted the Department of Homeland Security, which contacted Rhode Island state police.

A joint investigation was then launched by investigators from the Rhode Island State Fusion Center, the FBI's Joint Terrorism Task Force (JTTF) in Rhode Island, New York and New Jersey and the Bureau of Immigration and Customs Enforcement.

Investigators learned that when Mullawala obtained his driver's license from the Rhode Island Registry of Motor Vehicles, he gave a false statement indicating he was a Rhode Island resident. ICE then determined he was a citizen of India and in the United States on an expired temporary student visa.

On Tuesday, Mullawala went to state police headquarters thinking he was responding to another matter. He was then apprehended and turned over to ICE.

He's being held in the federal Suffolk County detention center in Boston until his immigration hearing in Boston, which is expected to be sometime within the next few weeks. He will be charged with overstaying his visa and is facing possible deportation back to India.

O'Donnell said his department, as well as the New York and New Jersey JTTFs, are investigating Mullawala's background and the residences he had in those three states.

Authorities have not yet turned up the names of any other specific individuals Mullawala may have been conspiring with.

"He didn't have family, he did have friends," O'Donnell said, adding that authorities are trying to track down people Mullawala was associated with in New York, where his most recent address is located.

That address is 161 84th Road in Jamaica, Queens, according to Rhode Island police. He also has a residence on Carpenter Street in Providence, R.I., which he apparently hasn't lived at since 2003.

Police are also studying a computer taken from one of Mullawala's residence, O'Donnell said, adding that the man apparently was a computer expert. They will look at his e-mails, as well as any Web sites he frequented. Any potential overseas connections will be handled by the FBI and DHS, O'Donnell said, although none have yet turned up.

An official at the New York JTTF office contacted by FOXNews.com said he could not comment on the status of this or any ongoing investigation.

More than 500,000 transportation workers — including school-bus drivers to mass transit workers — call in tips as part of the Highway Watch program, said spokesman John Willard. The Highway Watch ISAC vets the calls to determine which ones are substantial enough to pass on to federal authorities.

"We get a few hundred [calls] a month," Willard said. "They range from anything from 'there's a guy in his car on the side of a road' ... to 'I'm witnessing a crime' ... to 'there's this person who seems suspicious.'"

He added: "We've gotten a few of those we believe have led to very credible investigations."

The Highway Watch ISAC was first established by DHS in March of 2004. The original Highway Watch was set up in 1998 as a safety program and run by the American Trucking Association up until 2004. It added an anti-terrorism and security training program in the spring of 2002, which almost every major trucking company in the United States is now mandating for their drivers, Willard said.

The course teaches drivers how to keep themselves safe by always keeping their trucks locked, and not keeping the vehicles running when they're not in them. It also provides various emergency contact and tipline numbers.

But it also tells people what kinds of activity to be on the alert for.

"Casing," for example, can include activities such as an individual inquiring about details, of hazardous material deliveries. There was one situation in Florida where a man was seen videotaping hazardous material dropoffs, Willard said.

"We talk to them about how a typical terrorist act is carried out," he added. "Terrorists typically don't wake up on Tuesday morning and blow something up on Tuesday afternoon. It normally goes through an extensive process of targeting, casing, etc… The first thing we do is make drivers aware of that process."