
Suspects tied to Boston bombings —
Dias Kadyrbayev, left, with Boston Marathon bombing suspect Dzhokhar Tsamaev in a picture taken from the social media site VK.com. Kadyrbayev is expected to plead guilty August 21 to charges in connection with removing a backpack and computer from Tsamaev's dorm room after the April 2013 bombing, according to a defense lawyer.

Suspects tied to Boston bombings —
Bombing suspect Tamerlan Tsarnaev was killed during the shootout with police in Watertown, Massachusetts, on April 19, 2013. He is pictured here at the 2010 New England Golden Gloves.

Suspects tied to Boston bombings —
Dzhokhar Tsarnaev was captured in a Boston suburb on April 19, 2013, after a manhunt that shut down the city. In July, he pleaded not guilty to killing four people and wounding more than 200.

Suspects tied to Boston bombings —
From left, Azamat Tazhayakov and Dias Kadyrbayev went with Boston bombing suspect Dzhokhar Tsarnaev to Times Square in this photo taken from the social media site VK.com. A federal grand jury charged Tazhayakov and Kadyrbayev with obstructing justice and conspiracy to obstruct justice relating to the removal of a backpack from Tsarnaev's dorm room after the bombings. Tazhayakov was convicted of conspiracy and obstruction charges in July 2014. He faces up to 25 years in prison at his sentencing in October. He has filed an appeal.

Suspects tied to Boston bombings —
Robel Phillipos, a U.S. citizen, was also arrested on May 1, 2013. He was charged with lying to federal agents about the bombing, according to court papers.

Suspects tied to Boston bombings —
Phillipos, Tazhayakov and Kadyrbayev are accused of removing items from Tsarnaev's dorm room after the bombings on April 15, 2013. The items they took included a backpack containing fireworks that had been "opened and emptied of powder," according to the affidavit.

Suspects tied to Boston bombings —
The FBI released photos and video on April 18, 2013, of two men identified as Suspect 1 and Suspect 2 in the deadly bombings at the Boston Marathon. They were later identified as Dzhokhar Tsarnaev, 19, and his brother Tamerlan Tsarnaev, 26.

Suspects tied to Boston bombings —
Boston Police released surveillance images of Dzhokhar Tsarnaev at a convenience store on April 19, 2013.

Suspects tied to Boston bombings —
The FBI tweeted this photo on April 19, 2013, and urged Watertown residents to stay indoors as they searched for the second suspect.

Suspects tied to Boston bombings —
The FBI released photos and video on April 18, 2013, of two men it called suspects in the deadly bombings and pleaded for public help in identifying them. The men were photographed walking together near the finish line.

Suspects tied to Boston bombings —
A man identified as Suspect 2 appeared in this photograph by bystander David Green, who took the photo after completing the Boston Marathon. Green submitted the photo to the FBI, he told Piers Morgan in an interview.

Suspects tied to Boston bombings —
The man identified as Suspect 2 appears in a tighter crop of David Green's photo.

Suspects tied to Boston bombings —
Authorities later identified Suspect 1 as Tamerlan Tsarnaev.

Suspects tied to Boston bombings —
Suspect 2 was identified as Dzhokhar Tsarnaev.

Suspects tied to Boston bombings —
Suspect 1 walks through the crowd.

Suspects tied to Boston bombings —
Suspect 1 walks through the crowd.

Suspects tied to Boston bombings —
Suspect 1 walks through the crowd.

Suspects tied to Boston bombings —
Both suspects are seen walking through the crowd.

Suspects tied to Boston bombings —
Suspect 2 walks through the crowd.

Suspects tied to Boston bombings —
Suspect 2 walks through the crowd.

Suspects tied to Boston bombings —
A photo released by the FBI highlights Suspect 2.

Suspects tied to Boston bombings —