Tamerlan Tsarnaev practiced boxing at the Wai Kru Mixed Martial Arts center in Boston in this April 2009 photo.

Tamerlan Tsarnaev arrived at the Wai Kru Mixed Martial Arts center in Boston in this April 2009 photo.

Tamerlan Tsarnaev, with Somerville boxing club trainers, got his hands laced at a Golden Glove event in Lowell on May 15, 2006.

Tamerlan Tsarnaev, with Micky Ward, a former professional boxer, at a Golden Gloves event in Lowell on May 15, 2006.

Dzhokhar A. Tsarnaev was being sought by police in the Boston Marathon bombings.

Law enforcement officials identified two suspects in the Boston Marathon bombings as brothers Dzhokhar A. Tsarnaev (left) and Tamerlan Tsarnaev. Tamerlan was killed in a confrontation with police.

The suspects were photographed near the finish line.

What appears to be Dzhokhar A. Tsarnaev (left, in white hat) is shown walking away after the Marathon bombings on Monday.

Dzhokhar A. Tsarnaev in a photo release early Friday morning.

The Boston Marathon bombings killed three people and injured more than 170, some of whom lost limbs.

Dzhokhar A. Tsarnaev, in a yearbook photo, was a member of the class of 2011 at the Cambridge Rindge & Latin School.

An undated image of what appears to be Dzhokhar Tsarnaev taken from VKontakte, a Russian social media site.

Dzhokhar A. Tsarnaev was on the wrestling team in high school, former classmates said.

Dzhokhar A. Tsarnaev in an undated photo.

The FBI initially referred to Dzhokhar A. Tsarnaev, here in security camera footage shortly before the Marathon bombing, as Suspect 2.

“We believe this to be a terrorist,’’ Boston Police Commissioner Edward Davis told reporters. “We believe this to be a man here to kill people.”

The brothers killed an MIT police officer and later seriously injured a Transit Police officer, officials said.

Tamerlan Tsarnaev, initially known as Suspect 1, died early Friday morning after a shootout with police, officials said.

The brothers led law enforcement in a car chase and threw grenades at officers, injuring about 20 officers, officials said.

Tamerlan Tsarnaev’s injuries were inflicted by a combination of blasts and gunshots, said Dr. Richard Wolfe of Beth Israel Deaconess Medical Center.

When his brother was injured and apprehended, Dzhokhar A. Tsarnaev escaped.