The first suspect -- apparently Tamerlan Tsarnaev, according to authorities -- appears in the images wearing a dark hat, sunglasses and a backpack. The second suspect, wearing a white cap, police said, is the one who remained at large throughout Friday until he was taken into custody Friday night.
But the mother of the Tsarnaev brothers refused to believe they were involved in the marathon bombings and subsequent shootout.
"It's impossible for them to do such things. I am really telling you that this is a setup," Zubeidat Tsarnaeva told state-run Russia Today from Dagestan.
"My son would never keep it in secret. ...If there is anyone who would know it would be me. He wouldn't hide it. But there was never a word."
The brothers came from the Russian Caucasus region and moved to Kazakhstan at a young age before coming to the United States several years ago.
"My youngest was raised from 8 years in America. My oldest was really properly raised in our house. Nobody talked about terrorism," their mother said.
The suspects' parents recently returned to Dagestan in the Caucasus region after living in the United States for about 10 years because they were "nostalgic," the father, Anzor Tsarnaev, told Russian state-run Zvezda TV.
He accused someone of framing his sons. "I don't know who exactly did it. But someone did."
A federal official told CNN that Dzhokar Tsarnaev came to the U.S. as a tourist with his family in the early 2000s and later asked for asylum. He became a naturalized U.S. citizen in 2012. Tamerlan Tsarnaev was not a naturalized citizen, said the official, who spoke on condition of anonymity. He came "a few years later" and was lawfully in the United States as a green-card holder.
Tamerlan Tsarnaev had studied at Bunker Hill Community College and wanted to become an engineer, according to those who knew him. He then took a year off to train as a boxer.
The official said that a posting on a social media site in the elder brother's name included the comments: "I don't have a single American friend. I don't understand them."
Dzhokar Tsarnaev attended Cambridge Rindge & Latin, a public high school, said Eric Mercado, who graduated a year behind the suspect. Mercado said Tsarnaev had worked at Harvard University as a lifeguard.
"We hung out; we partied; we were good high school friends," Mercado told CNN.
"We're all, like, in shock. We don't really understand. There were no telltale signs of any kind of malicious behavior from Dzhokar. It's all coming as a shock, really."
Mercado said he lived a block away from the suspect and did not know his older brother.
Dzhokar Tsarnaev is currently registered as a student at University of Massachusetts Dartmouth, which ordered its campus evacuated on Friday. The school is located 65 miles south of Cambridge, just west of New Bedford.
Larry Aaronson, Dzhokar Tsarnaev's neighbor and a former teacher at the high school Tsarnaev attended, called him a "wonderful kid."
"He was so grateful to be here, he was compassionate, he was caring, he was jovial," Aaronson told CNN.