The case had apparently gone cold. But after several months of no progress, federal authorities have now zeroed in on a suspect in last year's shootings at several military sites around the nation's capital. Their suspect: the 22-year-old Marine reservist arrested Friday after causing a terror scare near the Pentagon.

Ballistics obtained at the suspect's home have been linked to evidence found at the scenes of the 2010 shootings, including the Marine Corps Museum in Triangle, Va., a vacant Marine recruiting station in Chantilly, Va., and the Pentagon itself, Fox News has learned.

Authorities are now trying to track down a vehicle once owned by the suspect, Yonathan Melaku of Alexandria, Va., who has since sold the vehicle.

Melaku was arrested early Friday morning at Arlington National Cemetery when the site was closed. He was carrying a backpack with what authorities initially thought might be explosives, and they found a notebook containing words and phrases such as "Taliban," "Al Qaeda," "defeated coalition forces," and "mujahedeen." The discoveries caused "concerns about the public’s safety," the FBI said at the time, and shut down major highways for much of Friday.

In the hours after Melaku's arrest Friday, FBI agents swarmed his home in Alexandria and interviewed neighbors.

Asked to confirm that evidence found in Melaku has been linked to last year's shootings, an FBI spokeswoman declined comment, citing "an ongoing investigation."

At a press conference in Washington in October, in the midst of the investigation into the shootings, a top FBI official said authorities believed the person responsible "has a grievance surrounding the U.S. Marine Corps."

“It may be that he feels he has been wronged by the Corps in his professional and or personal life,” said FBI Acting Assistant Director John Perren, whose Washington Field Office has been leading the FBI investigation. “The subject of his grievance does appear to be the institution of the United States Marine Corps and not the individual men and women Marines for whom he may feel a great deal of respect, admiration and even loyalty.”

Perren said authorities “do not believe it is his intention to harm innocent citizens or Marines,” adding that the suspect “has attempted to avoid casualties by acting during the nighttime and non-business hours.” In fact, no one was injured in any of the shootings.

Still, Perren said, “Acting out in this way however can lead to disastrous and tragic consequences that we all wish to avoid."

The first bullet holes were found Oct. 17, when $20,000 worth of windows and glass was shattered at the Marine Corps Museum. Two day later, six shots were fired into the south side of the Pentagon, which will be serving as a staging area for runners and others during the Marine Corps Marathon. The suspect then struck the recruiting center. Later in October, shots were fired again at the museum, apparently from the side of the building facing Interstate 95.

The shootings all occurred within 40 miles of each other in northern Virginia.

According to the FBI, Melaku joined the Marine Corps Reserve on Sept. 4, 2007, and he is currently listed as a motor vehicle operator with the Marine Corps reserves. He has previously been awarded the National Defense Service Medal and the Selected Marine Corps Reserve Medal. He has not been deployed overseas.