A grim hunt for answers in wake of attack

Investigators worked at the scene on Boylston Street, and hundreds of officers fanned out across the city Tuesday.

John Tlumacki/Globe Staff

Investigators worked at the scene on Boylston Street, and hundreds of officers fanned out across the city Tuesday.

Remains of a backpack the FBI says contained one bomb.

ASSOCIATED PRESS

Remains of a backpack the FBI says contained one bomb.

This image shows the remains of a pressure cooker that the FBI says was part of one of the bombs.

Associated Press

This image shows the remains of a pressure cooker that the FBI says was part of one of the bombs.

Emily Gillis, 7, her brother Conor, 4, of Dorchester, and their cousin Benjamin McCormick, 8, of Milton attended a vigil for blast victim Martin Richard at Garvey Park in Dorchester.

Yoon S. Byun/globe staff

Emily Gillis, 7, her brother Conor, 4, of Dorchester, and their cousin Benjamin McCormick, 8, of Milton attended a vigil for blast victim Martin Richard at Garvey Park in Dorchester.

Garvey Park in Dorchester was nearly filled with people during the vigil for Martin Richard, who was killed in Monday's blasts.

Yoon S. Byun/globe staff

Garvey Park in Dorchester was nearly filled with people during the vigil for Martin Richard, who was killed in Monday's blasts.

Sam Galvin of West Roxbury added candles to a make-shift memorial on the barricades blocking off Boylston Street.

Aram Boghosian for The Boston Globe

Sam Galvin of West Roxbury added candles to a makeshift memorial on the barricades blocking off Boylston Street.

Sisters Justine Lescarbeau (left) and Jocelyn Lescarbeau, both of Boston, sign a banner during a vigil and memorial on Boston Common.

Essdras M. Suarez/Globe Staff

Sisters Justine Lescarbeau (left) and Jocelyn Lescarbeau, both of Boston, sign a banner during a vigil and memorial on Boston Common.

Lizzie Lee, 56, of Lynwood, Wash., who was participating in her first Boston Marathon, holds a candle and a flower at a vigil at Boston Common.

Julio Cortez/AP

Lizzie Lee, 56, of Lynwood, Wash., who had participated in her first Boston Marathon, holds a candle and a flower at a vigil at Boston Common.

Members of the military walked along Boylston Street near the finish line of the Boston Marathon.

Aram Boghosian for The Boston Globe

Members of the military walked along Boylston Street near the finish line of the Boston Marathon.

The Red Sox had a moment of silence for victims before a game in Cleveland, playing the Indians at Progressive Field.

Mark Duncan/AP

The Red Sox had a moment of silence for victims before a game in Cleveland, playing the Indians at Progressive Field.

Sox second baseman Dustin Pedroia walked past a sign from an Indians fan in the dugout.

Mark Duncan

Sox second baseman Dustin Pedroia walked past a sign from an Indians fan in the dugout.

Investigators were combing through the aftermath of the deadly Boston Marathon terrorist attack Tuesday.

John Tlumacki/Globe Staff

Investigators were combing through the aftermath of the deadly Boston Marathon terrorist attack Tuesday.

The scene outside of Marathon Sports, the site of the first bomb explosion.

John Tlumacki/Globe Staff

The scene outside of Marathon Sports, the site of the first bomb explosion.

A woman looked down Boylston Street Tuesday, toward the finish line of the Boston Marathon and the site of deadly bombings a day earlier.

MATTHEW CAVANAUGH/EPA

A woman looked down Boylston Street Tuesday, toward the finish line of the Boston Marathon and the site of deadly bombings a day earlier.

A Boston Police officer stood on Boylston Street on Tuesday.

MATTHEW CAVANAUGH/EPA

A Boston Police officer stood on Boylston Street on Tuesday.

Boston Police Commissioner Edward Davis spoke along with other local and federal officials Tuesday morning.

Bill Greene/Globe Staff

Boston Police Commissioner Edward Davis spoke along with other local and federal officials Tuesday morning.

Senator Elizabeth Warren, Boston Mayor Thomas M. Menino, Governor Deval Patrick, and FBI special agent in charge Richard DesLauriers spoke at the press conference.

Elise Amendola/Associated Press

Senator Elizabeth Warren, Boston Mayor Thomas M. Menino, Governor Deval Patrick, and FBI special agent in charge Richard DesLauriers spoke at the press conference.

Speaking Tuesday afternoon at the White House, President Obama said,

Susan Walsh/Associated Press

Speaking Tuesday afternoon at the White House, President Obama said, "We do not know whether this is an act of an organization, or an individual, or individuals."

A military police officer checked the identification of a man on Massachusetts Avenue on Tuesday morning.

Darren McCollester/Getty Images

A military police officer checked the identification of a man on Massachusetts Avenue on Tuesday morning.

//c.o0bg.com/rf/image_90x90/Boston/2011-2020/2013/04/17/BostonGlobe.com/Metro/Images/tlumacki_bombaftermath095--90x90.jpg Bomb pieces, circuit board found; FBI requests tips

Investigators have found evidence that timing devices were used to detonate the bombs that ripped through Boston Marathon spectators.

A photo of Martin Richard, the 8-year-old boy killed in the Marathon bombing, holding this sign has come to symbolize the tragedy worldwide.

Photo of victim Martin Richard now a symbol

A photo of the 8-year-old boy killed in the Marathon bombing holding a peace sign has come to symbolize the tragedy worldwide.

//c.o0bg.com/rf/image_90x90/Boston/2011-2020/2013/04/17/BostonGlobe.com/Metro/Images/campbell-4288--90x90.jpg Krystle Campbell remembered as reliable

For grieving mother Patricia Campbell, the loss of her 29-year-old daughter at the Marathon attack “doesn’t make any sense.”

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Photos

Scenes from the marathon tragedy

VIDEOS

Scenes from the explosions

More coverage of the blasts

Greg and Jackie Pavek of Wisconsin have long come to the race, but may not be back.

Along Marathon route, grief and anger run deep

From Hopkinton to Boston, residents spoke of a sense of loss forged by years of cheering the runners on.

Opinion on the bombings

Kevin Cullen

Answering the call, in all its poignant horror

Selfless heroics were just part of the job for District 4 firefighters responding after Monday’s attack.

Sports

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red sox 7, indians 2

Will Middlebrooks, left, congratulated Dustin Pedroia and Jacoby Ellsbury after they scored on a bases-loaded double by Mike Napoli in the second inning.

Red Sox remain strong, top Indians

Mike Napoli doubled twice in a seven-run second inning as the Red Sox beat the Indians, 7-2.

Metro

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John J. O'Brien, former Massachusetts Department of Probation commissioner, now faces a federal case, but the date has not been set. He had resigned in 2010.

Former Mass. probation chief acquitted of conspiracy

John O’Brien was found not guilty in Suffolk Superior Court of multiple counts of conspiracy to commit bribery.

Business

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Wireless networks have not handled the sudden increases during disasters like hurricanes and the explosions that rocked the Boston Marathon and its fans on Monday.

Cellphone networks overwhelmed after blasts in Boston

Wireless networks have not handled increases during disasters like the explosions that rocked the Boston Marathon.

Nation & World

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President Obama also said he will not reward the provocative behavior recently exhibited by North Korean leader Kim Jong Un.

President Obama doubts North Korea ability

Obama does not believe North Korea has the ability to miniaturize a nuclear weapon to fit atop a missile.

Food & dining

A plate of gluten-free chickpea pasta from Rialto in Cambridge.

Gluten: fact or fad or a bit of both?

A gluten-free diet is important to millions, but its significance may be overblown.

Note to subscribers

All BostonGlobe.com stories are available to non-subscribers right now for coverage of the Boston Marathon explosions.

  

Magazine

The cover for the April 14 2013 issue

Greetings from Gun Valley
The cover for the April 7 2013 issue

The complete guide to Boston's food trucks
The cover for the March 31 2013 issue

The great running experiment
The cover for the March 24 2013 issue

Azores, a perfect destination for Boston travelers

Opinion

“The attack on the Boston Marathon was an assault on our civic life, our very ability to have fun together. So it is up to all of us to go the distance to make sure the Marathon survives.”

Derrick Z. Jackson