One year ago today, two backpack bombs were detonated at the Boston Marathon, killing three people. More than 260 others were wounded or maimed. In the months since, many man-hours have been spent investigating the accused perpetrators of the bombings, Tamerlan and Dzhokhar Tsarnaev. However, a key question remains unanswered: did the brothers have any substantive ties to terrorists abroad?

The extent of the confusion surrounding this basic question is troubling. Tamerlan Tsarnaev, the elder brother, is known to have traveled to Dagestan for several months in 2012. Credible press reports say that he was in contact with extremists participating in the insurgency against the Russian government there. But the U.S. government still has not provided the American public with a detailed summary of Tamerlan’s overseas contacts. And the press’s reporting does not clarify matters. Compare three recent accounts, all of which were published on April 9.

The first account is from The New York Times, which cited a senior American official who has been briefed on an inspector general’s investigation into the attack and any intelligence failures leading up to it. The investigation was conducted by several agencies in the U.S. intelligence community. The New York Times reported that federal authorities “have uncovered little evidence tying the brothers to an international terrorist organization” and the FBI, which is leading the investigation, has “found nothing that showed [Tamerlan Tsarnaev] received training or encouragement from terrorists.” A “senior official” who has been briefed on the report told the Times that the U.S. hasn’t “found anything substantive that ties them to a terrorist group.”

That sounds clear cut. It isn’t.

The Los Angeles Times published its own account of the investigation into the Tsarnaev brothers that same day. The L.A. Times led with an intriguing scoop: Tamerlan Tsarnaev had tried to legally change his first name to Muaz in honor of Emir Muaz, a jihadist who was killed in Dagestan in 2009. Emir Muaz (whose real name was Omar Sheykhulayev) was a senior leader in a group called the Vilayat Dagestan, which is a part of the al Qaeda-linked Islamic Caucasus Emirate, or Imarat Kavkaz (I.K.). Both the U.S. and United Nations have designated the I.K. a terrorist organization.

Citing “law enforcement officials,” the L.A. Times reported that Muaz “was also the nickname rebels had given [Tamerlan] Tsarnaev during his six-month visit to the region in 2012.” Moreover, U.S. officials said that while Tamerlan had “made an unsuccessful attempt to join the rebels,” he “was either sent back to the U.S. to carry out a terrorist strike or took it upon himself.”

That is, the L.A. Times’s sources left open the possibility that someone, likely within the Vilayat Dagestan or I.K., had sent Tamerlan Tsarnaev back to the U.S. in anticipation of the bombing. But they also did not rule out that he “took it upon himself.” (The Vilayat Dagestan issued a quasi-denial in the wake of the attack.) Either way, the picture that emerges in the L.A. Times is not of a man lacking “substantive” ties to an “international terrorist organization,” as The New York Times’s sources said.

Hours after the L.A. Times published its account, the Boston Globe offered another twist. According to the Globe, Tamerlan’s “inspiration” for changing his name “may have been different” from the motivation described by the L.A. Times. Instead of taking the name of a fallen terrorist, Tamerlan may have simply chosen the name “Muaz” because it was the same name as “an early Islamic scholar.” The Globe sourced this far more benign reading of Tamerlan’s attempted name change to his “associates in Dagestan.”

The motivation for Tamerlan’s name change is hardly the only unsettled issue.

Late last month, the House Homeland Security Committee released a report summarizing its investigation into the Boston Marathon bombings. The committee did not come up with a lot of answers. “It has not been determined whether the Boston Marathon bombing … is tied directly to the Caucasus Emirate or the ongoing terrorist activity in Dagestan, Chechnya, and across the North Caucasus,” the report reads. Tamerlan “possibly had the opportunity to meet with rebel fighters,” who “may have helped to fuel his radicalization,” but American “investigators have not found proof of these meetings.”

“Proof” in this case may be hard to come by. Some of the key personalities the elder Tsarnaev is suspected of interacting with are dead, as is Tamerlan himself. It is left to investigators to piece together the remaining threads of evidence and then judge for themselves whether they lead somewhere, or nowhere.

The committee’s report cites several such threads. Tamerlan reportedly visited a mosque in Makhachkala, Dagestan that is well-known for its extremist ties. According to The Wall Street Journal, for example, the mosque’s founder provide assistance to Ayman al Zawahiri, who took over as head of al Qaeda following Osama bin Laden’s death, during a trip to Dagestan in 1997.

Other press reporting suggests that Tamerlan met with Mahmoud Nidal, a known jihadist recruiter in Dagestan who was killed in 2012. According to the committee’s report, however, American officials in Moscow do not believe that the two ever met.

Tamerlan was in contact with William Plotnikov, a Canadian who shared Tamerlan’s love of boxing before heading down the extremist path. Plotnikov was killed while fighting in July 2012. Plotnikov was, presumably, a member of the Vilayat Dagestan or one of its associated groups. The two were in contact online, but it is not clear if they ever met in person. Just a few days after Plotnikov’s death, Tamerlan suddenly returned home to the United States. U.S. investigators see his abrupt departure as suspicious.

Based on his social media profile and other evidence, we know that Tamerlan Tsarnaev was drawn to the jihadist ideology that fuels groups such as the Vilayat Dagestan and the I.K. Did his time in Dagestan lead to something more? We still do not know.

Thomas Joscelyn is a senior fellow at the Foundation for Defense of Democracies and senior editor of The Long War Journal.