As the days press on, the investigation into the brothers Tsarnaev is turning up fewer and fewer leads explaining why they would decide to bomb innocent citizens at the Boston Marathon and then engage law enforcement in two days of intense firefights before being captured or killed. 

A picture began to emerge Saturday morning that showed the 26-year-old Tamerlan Tsarnaev as the potential influence on the 19-year-old Dzhokhar Tsarnaev, who is still in serious condition and has yet to speak with authorities as of Sunday morning, and the potential driving force behind their attack. Tamerlan was the dedicated, possibly radicalized Muslim follower who researched 9/11 conspiracies online and was prone to angry and potentially violent outbursts. "I used to warn Dzhokhar that Tamerlan was up to no good," Zaur Tsarnaev, an alleged cousin, told the Boston Globe. "He used to strike his girlfriend," the cousin added. "He was not a nice man." Tamerlan's Youtube channel also has a series of videos dedicated to 9/11 conspiracies. "[Dzhokhar is] just another victim of his older brother. He victimized others, but he’s been used by his older brother," uncle Ruslan Tsarni told the Today show. "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 former wrestling teammate of Dzhokhar's has theorizedThe Los Angeles Times' Andrew Tangel and Ashley Powers report Tamerlan was thrown out of a mosque service three months ago after shouting that Martin Luther King Jr. shouldn't be praised because he was not Muslim. The imam had held up a picture of the civil rights leader as an example of someone service attendees should try and emulate. Tamerlan was "crazy to me," one attendee said. He "was not really so nice," said another.

Tamerlan was having a difficult time adjusting to American life. He didn't "understand" Americans, he now famously told his boxing coach in 2009. On top of that, he recently had difficulties securing an American citizenship. The New York Times' Julia Preston reports Tamerlan Tsarnaev's F.B.I. investigation and interview "threw up red flags and halted" his application for American citizenship a few months ago. The Department of Homeland Security decided to delay granting his request for the time being once a background check revealed the F.B.I. interview. The F.B.I. also reportedly investigated Tamerlan within the last year, according to Preston. Dzhokhar had already been granted his American citizenship in 2012. 

Russia requested information about Tamerlan prior to a trip that saw him spend six months in or around Russia in 2012. There was suspicion that he may have connections to radical groups in Chechnya. They believed he was a "follower of radical Islam and a strong believer," but the following F.B.I. investigation didn't turn up any clues. They checked his online activity at the time, and interviewed Tamerlan and assorted family members before concluding he had no ties to any terrorism organization, domestic or foreign. This was prior to his six month trip. The F.B.I. requested the information from Russia that raised their concern but never heard back. 

For what it's worth, experts explained to Talking Points Memo's Hunter Walker that a request for information from Russia to the U.S. is fairly common place. "On terrorism issues, this is one of the few places where the United States and Russia maintain some semblance of a functional relationship," former Treasury Department official and Georgetown University professor Dr. Christopher Swift explained to Walker. Another said it was not unusual for Russia to request information on any 20-something Chechen requesting to travel to Russia. There was some speculation Tamerlan may have been connected to the Caucasus Emirate, a radicalized terrorist organization that resembles Al Qaeda in the brothers homeland, but the group has already denied any involvement in the bombing