A grim hunt for answers in wake of attack

A sign was taped to a barricade near the site of the bombings on Wednesday.

Bill Greene/Globe Staff

A sign was taped to a barricade near the site of the bombings on Wednesday.

Investigators combed through the scene of one of the blast sites on Wednesday morning.

Julio Cortez/Associated Press

Investigators combed through the scene of one of the blast sites on Wednesday morning.

Robert Bakoian of Boston prayed at the barricade to the crime scene at Boylston and Berkeley streets on Wednesday.

Bill Greene/Globe Staff

Robert Bakoian of Boston prayed at the barricade to the crime scene at Boylston and Berkeley streets on Wednesday.

Victoria Kichuk (left) of Brighton visited the makeshift memorial at Boylston and Berkeley streets.

Bill Greene/Globe Staff

Victoria Kichuk (left) of Brighton visited the makeshift memorial at Boylston and Berkeley streets.

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.

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

Reuters

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

Remains of what may have been part of the bomb.

Reuters

Remains of what may have been part of the bomb.

Remains of a backpack the FBI says contained one bomb.

ASSOCIATED PRESS

Remains of a backpack the FBI says contained one bomb.

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.

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.

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.

Five-year-old boy remains in critical condition

A doctor gave updates today on some of the injured, and the lid of one of the pressure cookers was reportedly found on the roof of a building near the blast site.

Suspicious letter mailed to Obama

The letter containing a “suspicious substance” comes a day after a letter was mailed to Senator Roger Wicker that tested positive for poisonous ricin.

//c.o0bg.com/rf/image_90x90/Boston/2011-2020/2013/04/17/BostonGlobe.com/Metro/Images/ab7ab413cb6d45d3bb5a476ce9457d13-ab7ab413cb6d45d3bb5a476ce9457d13-0-4234--90x90.jpg At hospitals, training for disasters gets put to test

At trauma centers across Boston Monday, doctors and nurses were pulled from treating routine chest pain and twisted ankles.

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.

Martin Richard, a symbol to many
Krystle Campbell, shown in July 2012, would have turned 30 on May 3. She was known as a tireless worker and a loyal friend and relative.

Krystle Campbell, ever reliable
Boston Marathon bomb scene pictures taken by investigators show the remains of an explosive device.

Photo gallery

Bomb remnants

Photos

Scenes from the marathon tragedy

More coverage of the blasts

Emily Gillis, 7, brother Conor, 4, of Dorchester, and their cousin Benjamin McCormick, 8, of Milton were among those at a vigil Tuesday night at Garvey Park in Dorchester in memory of Martin William Richard, 8, killed in the bombings.

Thousands honor Marathon victims with vigils

Across the region, people honored the victims of the attack, holding candles, reciting prayers, and vowing to never forget.

Opinion on the bombings

JOANNA WEISS

How do you tell a child about the Boston Marathon blasts?

This is school vacation week, and kids are expecting a week of heightened fun. How do you reconcile that with the terrible events of Monday?

Sports

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Fans can expect to see increased police presence at sporting events after the attack at the Boston Marathon.

Boston set to ramp up security for sporting events

When the Bruins host the Sabres Wednesday in the city’s first game since the attacks, fans can expect security to be extremely tight.

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