A look at the Boston Marathon bombing investigation thus far, a week after the death of Tamerlan Tsarnaev and the capture of his brother, Dzhokhar.
The Tsarnaevs are ethnic Chechens from the former Soviet republic of Kyrgyzstan. In 1992, they moved to their historic homeland of Chechnya, a restive region of southern Russia, but in 1994 the first war between Moscow and the regional separatists broke out. The Tsarnaevs moved back to Kyrgyzstan and from there in 1999 to neighboring Dagestan. In 2002, they immigrated to the United States. The parents returned to Dagestan a year ago while their sons and two daughters remained in the U.S.
Who was "Misha?'' In the years before the bombings, Tamerlan Tsarnaev came under the influence of a new friend, a Muslim convert who steered him to a strict strain of Islam. Under the tutelage of the friend, known only as Misha, Tamerlan gave up boxing and stopped studying music, family members said. He began opposing the wars in Afghanistan and Iraq. He turned to websites and literature that claimed the CIA was behind the terrorist attacks of Sept. 11, 2001. "Somehow, he just took his brain,'' said Tamerlan's uncle, Ruslan Tsarni, who recalled conversations with Tamerlan's father, who was worried about Misha's influence.
A brother's influence: Throughout his religious makeover, Tamerlan maintained a strong influence over his siblings, including Dzhokhar. "They all loved Tamerlan. He was the eldest one and he, in many ways, was the role model for his siters and his brother,'' said Elmirza Khozhugov, 26, the ex-husband of Tamerlan's sister, Ailina. "You could always hear his younger brother and sisters say, 'Tamerlan said this,' and 'Tamerlan said that.'"
Inspire:When Dzhokhar Tsarnaev spoke to investigators Sunday, he indicated that he and his brother learned to make bombs out of pressure cookers from Inspire, an online al-Qaida magazine. The terrorist magazine's first issue came out in mid-2010, and contained instructions in articles with titles like "Make a Bomb in the Kitchen of Your Mom.''
An FBI affidavit released this week said the bombs were made of "low-grade explosives'' packed into pressure cookers along with ''metallic BBs and nails.''
Fireworks purchase: Tamerlan Tsarnaev purchased two reloadable mortar kits from a Seabrook, N.H., store on Feb. 6, a company official said. Consumer-grade fireworks contain a limited amount of explosives, but the 48 pyrotechnic shells Tsarnaev obtained would have been enough to yield some black powder, Phantom Fireworks vice president William Weimer said in an interview with the Associated Press. Tsarnaev paid $199.99 in cash and walked out with his two "Lock and Load'' fireworks kits, Weimer said, consulting store records.
The trigger mechanism: The Los Angeles Times, citing a federal law enforcement official, reported that the bombs were triggered by long-range remote controls for toy cars - a more sophisticated design than originally believed - bolstering a theory that Tamerlan Tsarnaev may have received coaching on his six-month trip to Russia last year.
Information from the Associated Press, New York Times and Los Angeles Times was used in this report.