Tamerlan Tsarnaev’s YouTube account has been an object of fascination and speculation since journalists and Web users first found it just hours after the Boston bombing suspect's name was released. There's been particular attention on the two videos he placed in a playlist labeled "terrorism," which involves a Dagestani jihadist virtually unknown outside his region.

The videos could hint at Tsarnaev’s knowledge of foreign terrorists, at least one expert says. Investigators say they have ruled out the possibility that Tamerlan and his brother worked with an outside group, but the Internet is a big place, and the corners where Tsarnaev may have spent his time could give some clues as to what he believed.

The jihadist in the videos is Gadzhimurad Dolgatov, who used the nom de guerre Abu Dujana and was the commander of a small insurgent group until he was killed by Russian security forces not long into his career.

Even piecing together that much information about Dolgatov is difficult. An apparently obscure figure, he rarely shows up in mainstream media, even in Russia. Most of his videos have been pulled from YouTube. And, according to regional experts, he wasn’t an important figure even within his own movement.

“There are hundreds of minor commanders within the North Caucasus insurgency,” explained Aslan Doukaev, a Chechen journalist and director of Radio Free Europe’s North Caucasus service, via e-mail. There’s an overarching regional separatist group called the Caucasus Emirate, Doukaev explained, headed by a man named Doku Umarov. Within the Caucasus Emirate's claimed territory, there are several vilayahs, or provinces, such as Dagestan and Chechnya. Within those, there is a jumbled, confusing variety of provincial fronts, sectors and semi-autonomous fighting groups that loosely associate with one another.

Dolgatov was the commander of a small group in a small (but historically unstable) district: Kizilyurt, a 62,000-person region of Dagestan, says Liz Fuller, an analyst who has followed Chechnya since 1994.

But what Dolgatov did in that role, and how long he held it, is a matter of some uncertainty. Fuller estimates that he rose to prominence less than two years ago. According to D.C.-based research group the Jamestown Foundation, the previous leader of the Kizilyurt group died in late July 2012, which would make Dolgatov's time frame even shorter.

In either case, Dolgatov made several video missives during his tenure. The Russian-language videos, many of which show a clean-shaven Dolgatov with masked, gun-toting men, circulated on several local insurgent sites. In his videos, Fuller says, Dolgatov is articulate and quotes the Koran from memory in fluent Arabic. He also encourages young Muslims to embrace jihad; in one video, he says, “if you think Islam can be spread without spilling a single drop of blood, you're wrong,” and, later, “only cowards and hypocrites seek excuses not to join the jihad.”

But the interesting thing about Dolgatov in particular is his obscurity. Law enforcement officials do not believe there is any link between the Tsarnaevs and outside terrorist groups. Even so, the fact that Tsarnaev even knew about this minor Dagestani terrorist seems to suggest that the young man had unusually detailed knowledge of the groups, North Caucasus expert Cerwyn Moore told the Guardian.

"He's obviously aware of some of the clandestine groups operating in Dagestan,” Moore said. “This is a small sub-group. Abu Dujana is not a big player. Federal forces have been successful recently at killing all the top leaders."

Russian forces killed Dolgatov, according to CNN and Russian media, in late December 2012. One month after Dolgatov had posted a video threatening to assassinate the Kizilyurt police chief, Russian security forces raided the Makhachkala apartment where Dolgatov was staying. He and as many as five others died in the ensuing firefight.

“Several gunmen, who committed murders, extortions, robberies and armed attacks were blocked at a residential house,” reads an account from Russia’s state-owned ITAR-TASS news service. “Three of them were identified as Gadzhimurad Dolgatov, who according to the information of the National Anti-Terrorism Committee, was the warlord; Arsen Kuramagomedov, who was his accomplice; and the host of the flat, Shamil Akhmedov.”

But insurgent media, unsurprisingly, remembered Dolgatov differently: as a hero who defended local Muslims from torture and abuse, including at the hands of local police. On VDagestan, an insurgent Web site, commenters called Dolgatov a “martyr” and a “brave lion of Allah.”

“It is necessary to renew martyrdom attacks,” wrote another.

It's not clear how or why Tsarnaev came to know about Dolgatov and his career as a North Caucasus jihadist. But whether he stumbled upon Dolgatov's videos by chance or was more closely following the ins and outs of Dagestan insurgent groups, Tsarnaev appears to have ultimately followed the jihadist's path from extremism to death.