Zubeidat Tsarnaeva, mother to Boston bombings suspect Tamerlan Tsarnaev, claims he called her right before the deadly shootout that took his life. Johannes Hirn

Less than a week after the Boston Marathon bombings, Tamerlan Tsarnaev, one of the two brothers apparently behind the incident, is dead, but many questions about him remain. Where did Tsarnaev learn to create bombs? Was he connected to wider radical groups? And who influenced the young man and his teenage brother to commit mass murder?

Tamerlan Tsarnaev, who was killed in a shootout with police in Watertown, Mass., early Friday morning, was described by the FBI as a radical Muslim with possible ties to foreign extremist groups. But interviews with family members indicate that Tamerlan wasn’t always so intense about his faith. At some point over the last few years, he appears to have been seduced into a radical strain of Islam, and it seems he may have pushed his brother and collaborator Dzhokhar down the same path.

Before he was an accused (and now deceased) terrorist, Tamerlan Tsarnaev was a boxer. In a now famous photo essay series by Johannes Hirn, Tsarnaev explained that he felt alientated in the United States and did not have "a single American friend." He also explained his strict adherence to Islam, complaining that most Americans are too undisciplined in this day and age. In the interview, Tsarnaev comes off as austere, maybe even a little harsh, but not exactly evil. But behind that facade, something sinister was brewing. A simple glance at Tsarnev's YouTube channel shows bookmarks dedicated to terrorism and radical Islam, a likely sign that his disaffection with America was growing.

On Friday, the FBI announced that in 2011, it interviewed Tamerlan Tsarnaev for possible connections to terrorist organizations at the behest of an unnamed foreign government presumed to be Russia. The FBI says it investigated Tamerlan thoroughly, but found no link to terrorist organizations.

"The request stated that it was based on information that he was a follower of radical Islam and a strong believer, and that he had changed drastically since 2010 as he prepared to leave the United States for travel to the country's region [i.e. Chechnya and neighboring Dagestan] to join unspecified underground groups," the FBI said in a statement.

“The FBI did not find any terrorism activity, domestic or foreign, and those results were provided to the foreign government in the summer of 2011,” the statement continues.

While this information may appear to be a large red flag now, Talking Points Memo notes that Russia frequently requests information on young men visiting the Chechen region, making the request for more information on Tsarnaev seem less suspicious.

“These are routine,” Georgetown University professor Christopher Swift told TPM of Russia’s request to the FBI. “It wouldn’t be too surprising for the Russians to ask for information on any Chechen visa applicant — certainly 20-something males.”

Typically, Russia would be looking for ties to the Caucasus Emirate, a radical Islamic and separatist group in the wild North Caucasus region that is waging a jihadist fight against Russia. And while some sources have speculated that Tamerlan’s actions were related to the "emirate," the group released a statement Sunday denying any responsibility for the Boston Marathon bombings.

But that does not mean that Tsarnaev had no ties to the rebel group. According to NBC, Tsarnaev traveled to Russia in 2012, possibly under an alias, although his actions there are not known. And if the FBI’s statement that Tsarnaev planned to “join unspecified underground groups” is true, then it seems possible that he least attempted to make contact with the Caucasus Emirate while in the region. The Caucasus Emirate’s statement disavowed the bombing but did not rule out any affiliation with Tsarnaev.

While Tamerlan Tsarnaev may or may not have gained military expertise in Russia, his family members believe the seeds of radicalization were planted at home in the United States. Tsarnaev’s estranged uncle in Maryland, Ruslan Tsarni, stated that he was “shocked” by Tamerlan’s radicalization as far back as 2009 in an interview with NBC’s “Today Show.” Tsarni stated that an unnamed person may have pushed Tsarnaev down a radical path before his trip to Russia.

“There certainly were mentors,’’ Tsarni said. “I was shocked when I heard his words, his phrases, when every other word he starts sticking in words of God. I question what he’s doing for work, (and) he claimed he would just put everything in the will of God. It was a big concern to me. ... It wasn’t devotion, it was something, as it’s called, being radicalized. Not understanding what he is talking about. He is just using words for the sake of the words and not understanding the meaning of it.’’

“He said there is someone who brainwashed him, some new convert to Islam. I would like to stress (the acquaintance was) of Armenian descent,” Tsarni said in the interview. (Armenians, another Caucasian people, are historically Christian.) “It had nothing to do with Russia or with Chechnya. It started here.”

Tsarni also speculated that Tamerlan had influenced and coerced his kid brother Dzhokhar into orchestrating the bombings. Dzhokhar, who was captured Friday night hiding in a boat, alive but gravely wounded, had been described by many sources as much more relaxed than his brother.

“He’s just another victim of his older brother. He victimized others, but he’s been used by his older brother,” Tsarni said.

Ultimately, Tsarni concluded that his nephews were part of a larger operation, influenced by others to orchestrate the bombings. "I strongly believe they were just puppets and executors of something of bigger scale," he stated, though he did not clarify which groups he believes were pulling the strings.

Other people who knew the two also speculated that Tamerlan felt alienated in the United States and was drawn to radical Islam, eventually pushing his brother down the same dark path.

"Tamerlan maybe felt like he didn’t belong, and he might have brainwashed Dzhokhar into some radical view that twisted things in the Koran," a friend of Dzhokhar's told the New Yorker.

Were the two brothers simply a part of a greater plot? With Tamerlan dead and Dzhohkar in critical condition and unable to speak, it may be some time before we know for sure, if ever.