AD Main Menu

FBI issues photos of 2 suspects in Boston bombing

Denise Lavoie,Adam Geller
Neighbors sit outside the house of Krystle Campbell's parents in Medford, Mass.,Tuesday, April 16, 2013. Campbell was killed in Monday's explosions at the finish line of the Boston Marathon.
Michael Dwyer
The Federal Bureau of Investigation is seeking information regarding the two individuals pictured in this surveillance video prior to Monday's Boston Marathon bombings. The suspect in the white cap allegedly set down his backpack at the scene.
Unknown
Flowers sit at a police barrier near the finish line of the Boston Marathon in Boston Tuesday, April 16, 2013.
Winslow Townson
Investigators inspect the roof of the Lord & Taylor store where a surveillance camera is placed, center, which, an official said, is crucial in the investigation of the explosions near the Boston Marathon finish line, Thursday, April 18, 2013, in Boston.
Julio Cortez
The Orlando Magic and the Miami Heat teams observe a moment of silence for the victims of the Boston Marathon explosions before their NBA basketball game, Wednesday, April 17, 2013, in Miami.
David Santiago
Investigators comb through Boylston Street just beyond the finish line of the Boston Marathon, two days after two bombs exploded, Wednesday, April 17, 2013, in Boston. Authorities investigating the deadly bombings have recovered a piece of circuit board that they believe was part of one of the explosive devices, and also found the lid of a pressure cooker that apparently was catapulted onto the roof of a nearby building, an official said Wednesday.(AP Photo/Julio Cortez)
Julio Cortez
Mourners attend candlelight vigil for Martin Richard at Garvey Park, near Richard's home in the Dorchester section of Boston, on Tuesday, April 16, 2013. Martin is the 8-year-old boy killed in the Boston Marathon bombing.
Josh Haner
Neighbors hug outside the home of the Richard family in the Dorchester neighborhood of Boston, Tuesday, April 16, 2013. Martin Richard, 8, was killed in Monday's bombing at the finish line of the Boston Marathon.
Michael Dwyer
The Federal Bureau of Investigation is seeking information regarding two individuals including this one pictured in surveillance video prior to Monday's Boston Marathon bombings. This suspect in the white cap allegedly set down his backpack at the scene.
Unknown
Investigators in haz-mat suits examine the scene of the second bombing on Boylston Street in Boston Tuesday, April 16, 2013 near the finish line of the 2013 Boston Marathon, a day after two blasts killed at least three and injured over 170 people.
Elise Amendola
A investigator, right, takes a photograph on the roof of a building adjacent to the area where a bomb exploded near the Boston Marathon finish line, Thursday, April 18, 2013, in Boston as investigators fanned out across the streets, rooftops and awnings around the blast site in search of clues.
Julio Cortez
Eugene, Ore. runners gather for a 26 second moment of silence as part of a ÒRun for BostonÓ tribute at Alton Baker Park Wednesday, April 17, 2013 in Eugene, Ore. Nearly 300 runners participated in the evening gathering and run as part of a national movement to support the people affected by the Boston Marathon bombing.
Chris Pietsch
Investigators comb through the post finish line area of the Boston Marathon at Boylston Street, two days after two bombs exploded just before the finish line, Wednesday, April 17, 2013, in Boston. Authorities investigating the deadly bombings have recovered a piece of circuit board that they believe was part of one of the explosive devices, and also found the lid of a pressure cooker that apparently was catapulted onto the roof of a nearby building, an official said Wednesday.(AP Photo/Julio Cortez)
Julio Cortez
Lizzie Lee, 56, of Lynwood, Wash., who was participating in her first Boston Marathon and 11th overall, holds a candle and a flower at Boston Common during a vigil for the victims of the Boston Marathon explosions, Tuesday, April 16, 2013, one day after bombs exploded at the finish line of the Boston Marathon.
Julio Cortez
From right, Orlando Magic's Tobias Harris, Andrew Nicholson, Al Harrington, Nikola Vucevic, Kyle O'Quinn and Maurice Harkless observe a moment of silence for the victims of the Boston Marathon explosions before an NBA basketball game against the Chicago Bulls, Monday, April 15, 2013, in Orlando, Fla.
John Raoux
Sarah Shallbetter cries as she watches a broadcast of President Barack Obama speaking at an interfaith service at Cathedral of the Holy Cross on a video screen at the BoMA restaurant in Boston Thursday, April 18, 2013. The service was held in the wake of Monday's Boston Marathon explosions, which killed at least three and injured more than 140.
Matt Rourke
Two men in haz-mat suits investigate the scene of the first bombing on Boylston Street in Boston Tuesday, April 16, 2013 near the finish line of the 2013 Boston Marathon, a day after two blasts nearby killed three and injured over 170 people.
Elise Amendola
Investigators inspect the roof of a building adjacent to the area where a bomb exploded near the Boston Marathon finish line, Thursday, April 18, 2013, in Boston. The city continues to cope following Monday's explosions at the marathon.
Julio Cortez
A South Korean protester holds a banner during a demonstration against the deadly Boston Marathon bombings, near the U.S. Embassy in Seoul, South Korea Thursday, April 18, 2013.
Kin Cheung
A photograph of Boston University student Lingzi Lu, who was killed in the Boston Marathon explosions, sits on a table as a student writes a message on a board outside the school's Marsh Chapel before a vigil, Wednesday, April 17, 2013, in Boston. The city continues to cope following Monday's explosions near the finish line of the marathon, which claimed three lives. (AP Photo/Julio Cortez)
Julio Cortez
This image from a Federal Bureau of Investigation and Department of Homeland Security joint bulletin issued to law enforcement and obtained by The Associated Press, shows the remains of a pressure cooker that the FBI says was part of one of the bombs that exploded during the Boston Marathon. The FBI says it has evidence that indicates one of the bombs was contained in a pressure cooker with nails and ball bearings, and it was hidden in a backpack.
Unknown
President Barack Obama turns to leave after speaking in the Brady Press Briefing Room of the White House in Washington, Tuesday, April 16, 2013, following the explosions at the Boston Marathon.
Charles Dharapak
President Barack Obama speaks at the "Healing Our City: An Interfaith Service" at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013. The service is dedicated to those who were gravely wounded or killed in MondayÕs bombing near the finish line of the Boston Marathon.
Susan Walsh
Nursing students Katie Robinson, left, and Megan Beach listen to a broadcast on their phones from outside an interfaith service attended by President Barack Obama at the Cathedral of the Holy Cross, held in the wake of Monday's Boston Marathon explosions, which killed at least three and injured more than 140, Thursday, April 18, 2013, in Boston.
Matt Rourke
Rolando Muniz holds onto his daughter, Sara, 11, as they near the finish line of a 2.62 mile run on Wednesday, April 17, 2013 in Abilene, Texas. Members of the Abilene Runners Club along with others in the community joined together to participate in the Ò4.15.13Ó Run at Redbud Park.
Joy Lewis
Rita Ferullo, center, holds hands with other worshipers during a memorial service for Boston Marathon bombing victim Krystle Campbell at Grace Episcopal Church in Medford, Mass., Wednesday, April 17, 2013. (AP Photo/Michael Dwyer)
Michael Dwyer
This image from a Federal Bureau of Investigation and Department of Homeland Security joint bulletin issued to law enforcement and obtained by The Associated Press, shows the remains of a black backpack that the FBI says contained one of the bombs that exploded during the Boston Marathon. The FBI says it has evidence that indicates one of the bombs that exploded in the Boston Marathon was contained in a pressure cooker with nails and ball bearings, and it was hidden in a backpack.
Unknown
A mourner places a note with flowers at a police barricade near the finish line of the Boston Marathon in Boston Tuesday, April 16, 2013.
Winslow Townson
Patrons at BoMA restaurant view on a video screen President Barack Obama speak during an interfaith service at Cathedral of the Holy Cross, held in the wake of Monday's Boston Marathon explosions, which killed at least three and injured more than 140, Thursday, April 18, 2013, in Boston.
Matt Rourke
In this Wednesday, April 17, 2013 photo, Chinese hold pictures of Lu Lingzi, a Boston University graduate student from China who was killed Monday in the Boston Marathon explosions, as they hold candles to mourn for her in Shenyang in northeast China's Liaoning province. Lu was a graduate student studying mathematics and statistics and scheduled to receive her graduate degree in 2015.
Unknown
A Boston Bruins jersey with the Boston area code hangs in the locker of Bruins player Jay Pandolfo at TD Garden in Boston, Wednesday, April 17, 2013, after an NHL hockey game against the Buffalo Sabres in the aftermath of Monday's Boston Marathon bombings.
Jimmy Golen
Two theology students embrace following a vigil for Boston University student Lingzi Lu, who was killed in the Boston Marathon explosions, outside the school's Marsh Chapel, Wednesday, April 17, 2013, in Boston. The city continues to cope following Monday's explosions near the finish line of the marathon, which claimed three lives. (AP Photo/Julio Cortez)
Julio Cortez
A young woman carries a pair of running shoes and places them on the path of a prayer labyrinth to remember those killed and injured at the Boston Marathon yesterday during a prayer service at Monte Sano United Methodist Church Tuesday, April 16, 2013 in Huntsville, Ala.
Eric Schultz
Reginald Bohannon, of Atlanta, holds a United States flag as he stands outside the Big Peach Running Co. after taking part in an organized moment of silence and memorial run to show solidarity with victims of the Boston Marathon bombing, Tuesday, April 16, 2013, in Atlanta. The explosions Monday afternoon killed at least three people and injured at least 100 others.
David Goldman
A memento of flowers in a running shoe rests at a makeshift memorial in Boston's Back Bay neighborhood on Thursday, April 18, 2013, a few blocks from the finish line of the Boston Marathon, where people continue to bring special objects to mourn and honor those who were killed and injured after two bombs exploded at the finish line of the race.
Craig Ruttle
President Barack Obama speaks during an interfaith healing service at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013, for victims of Monday's Boston Marathon explosions.
Charles Krupa
Fans hold up a sign during the second period of an NHL hockey game between the Boston Bruins and the Buffalo Sabres in Boston Wednesday, April 17, 2013.
Elise Amendola
Jennifer Krewalk attends a makeshift memorial on Boylston Street near the finish line of Monday's Boston Marathon explosions, which killed at least three and injured more than 140, Wednesday, April 17, 2013, in Boston. (AP Photo/Matt Rourke)
Matt Rourke
A commemorative ribbon representing the New York Yankees and the Boston Red Sox is shown on the scoreboard as New York Yankees outfielders observe a moment of silence before a baseball game at Yankee Stadium in New York, Tuesday, April 16, 2013.
Kathy Willens
Investigators in haz-mat suits examine the scene of the second bombing on Boylston Street in Boston Tuesday, April 16, 2013 near the finish line of the 2013 Boston Marathon, a day after two blasts killed three and injured over 170 people.
Elise Amendola
Investigators sift through evidence on Boylston Street, just up from the finish line of the Boston Marathon in Boston, Thursday, April 18, 2013.
Winslow Townson
President Barack Obama speaks at the "Healing Our City: An Interfaith Service" at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013. The service is dedicated to those who were gravely wounded or killed in MondayÕs bombing near the finish line of the Boston Marathon.
Susan Walsh
A mourner reacts during a candlelight vigil in the aftermath of Monday's Boston Marathon explosions Wednesday, April 17, 2013, at City Hall in Cambridge, Mass.
Matt Rourke
Richard Maldonado lights a candle at a makeshift memorial on Boylston Street near the finish line of Monday's Boston Marathon explosions, which killed at least three and injured more than 140, Wednesday, April 17, 2013, in Boston. (AP Photo/Matt Rourke)
Matt Rourke
The crowd sings along to "Sweet Caroline" as a tribute to the victims of the Boston Marathon explosions before the bottom of the eighth inning of a baseball game between the Miami Marlins and the Washington Nationals, Tuesday, April 16, 2013, in Miami. The song by Neil Diamond has been a longtime fixture as a fan sing-along during the bottom of the eighth inning of Boston Red Sox games.
Wilfredo Lee
Flowers sit at a police barrier near the finish line of the Boston Marathon in Boston, Tuesday, April 16, 2013.
Winslow Townson
Investigators, bottom, inspect the roof of a building across the street from the area where a bomb exploded near the Boston Marathon finish line while others inspect items on Boylston Street, Thursday, April 18, 2013, in Boston.
Julio Cortez
President Barack Obama and first lady Michelle Obama attend an interfaith healing service at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013, for victims of Monday's Boston Marathon explosions.
Charles Krupa
A woman reflects in front of a makeshift memorial honoring Boston University student Lingzi Lu, who was killed in the Boston Marathon explosions, Wednesday, April 17, 2013, in Boston. The city continues to cope following Monday's explosions near the finish line of the marathon, which claimed three lives.
Julio Cortez
A makeshift memorial including a pair of running shoes sits on the campus of Boston University after it was learned that BU student Lu Lingzi was one of the victims of the Boston Marathon bombings in Boston Wednesday, April 17, 2013. (AP Photo/Winslow Townson)
Winslow Townson
Philadelphia Phillies center fielder Ben Revere runs off the field with tape on his glove that says 'Pray for Boston,' for the victims of the Monday bombings at the Boston Marathon, in the fifth inning of a baseball game against the Cincinnati Reds, Tuesday, April 16, 2013, in Cincinnati.
Al Behrman
Two men in haz-mat suits investigate the scene near the first bombing on Boylston Street in Boston Tuesday, April 16, 2013 near the finish line of the 2013 Boston Marathon, a day after two blasts nearby killed at least three and injured over 170 people.
Elise Amendola
Diners sit at an outdoor cafe on Newbury Street in Boston Thursday, April 18, 2013, while military police guard an intersection near the place where two bombs exploded at the finish line of Monday's Boston Marathon.
Winslow Townson
Massachusetts Gov. Deval Patrick hugs President Barack Obama as Obama was introduced to speak at the "Healing Our City: An Interfaith Service" at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013. The service is dedicated to those who were gravely wounded or killed in MondayÕs bombing near the finish line of the Boston Marathon.
Susan Walsh
John Reilly, right, watches as his son John, Jr., lights a candle during a memorial service for Boston Marathon bombing victim Krystle Campbell at Grace Episcopal Church in Medford, Mass., Wednesday, April 17, 2013. Reilly, Sr., is brother to Patty Campbell, Krystle's mother.
Michael Dwyer
Officials in tactical gear stand guard behind a Boston Police Department barricade near the site of the Boston Marathon explosions, Wednesday, April 17, 2013, in Boston. The city continues to cope following Monday's explosions near the finish line of the marathon. Authorities investigating the deadly bombings have recovered a piece of circuit board that they believe was part of one of the explosive devices, and also found the lid of a pressure cooker that apparently was catapulted onto the roof of a nearby building, an official said Wednesday. (AP Photo/Julio Cortez)
Julio Cortez
Atlanta Hawks forward Dahntay Jones, center, observes a moment of silence for victims of the Boston Marathon explosions before their NBA basketball game against the Toronto Raptors, Tuesday, April 16, 2013, at Philips Arena in Atlanta.
Dave Tulis
Karen Kaye, right, communications and community relations director for Big Peach Running Co., embraces Reginald Bohannon, of Atlanta, before the start of an organized moment of silence and memorial run to show solidarity with victims of the Boston Marathon bombing, Tuesday, April 16, 2013, in Atlanta. The explosions Monday afternoon killed at least three people and injured more than 170.
David Goldman
Investigators inspect the roof of a building adjacent to the area where a bomb exploded near the Boston Marathon finish line, Thursday, April 18, 2013, in Boston. Investigators in white jumpsuits fanned out across the streets, rooftops and awnings around the blast site in search of clues.
Julio Cortez
President Barack Obama and first lady Michelle Obama are escorted after attending the "Healing Our City: An Interfaith Service" at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013. The service is dedicated to those who were gravely wounded or killed in MondayÕs bombing near the finish line of the Boston Marathon.
Susan Walsh
Investigators comb through the post finish line area of the Boston Marathon at Boylston Street, two days after two bombs exploded just before the finish line, Wednesday, April 17, 2013, in Boston.
Julio Cortez
Boston University student Joy Liu places a note at a memorial on the campus for Boston Marathon bombing victim Lu Lingzi in Boston Wednesday, April 17, 2013. Lu and two friends had been watching the Boston Marathon near the finish line. (AP Photo/Winslow Townson)
Winslow Townson
St. Louis Cardinals shortstop Pete Kozma waits between hitters as rain starts to fall over PNC Park during a baseball game against the Pittsburgh Pirates Tuesday, April 16, 2013 in Pittsburgh. The flags are at half staff in memory of the victims of the Boston Marathon bombings.
Gene J. Puskar
Runners jog along Peachtree Street as part of an organized moment of silence and memorial run to show solidarity with victims of the Boston Marathon bombing, Tuesday, April 16, 2013, in Atlanta. The explosions Monday afternoon killed at least three people and injured at least 170 others.
David Goldman
Investigators inspect the roof of a building adjacent to the area where a bomb exploded near the Boston Marathon finish line, Thursday, April 18, 2013, in Boston.
Julio Cortez
Cellist Yo-Yo Ma performs during an interfaith healing service at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013, for victims of Monday's Boston Marathon explosions.
Charles Krupa
Jillian Blenis, 30, of Boston, reacts while stopping at a makeshift memorial, Wednesday, April 17, 2013, in Boston. The city continues to cope following Monday's explosions near the finish line of the Boston Marathon. (AP Photo/Julio Cortez)
Julio Cortez
An FBI investigator walks down a fire truck escalator with a bag from a building at the corner of Boylston Street and Fairfield Street , Wednesday, April 17, 2013, in Boston. Investigators in white jumpsuits fanned out across the streets, rooftops and awnings around the blast site in search of clues on Wednesday. (AP Photo/Julio Cortez)
Julio Cortez
Ann Kurtis, 51, of Livonia, is comforted by Patrice Esse, right, of Grosse Pointe Farms, after meeting with members of the Downtown Runners and Walkers group after their weekly run being held in honor of the victims of the Boston Marathon explosions on Tuesday April 16, 2013 in Detroit. Kurtis crossed the Boston finish line five minutes before the bombs went off.
Ryan Garza
Los Angeles International Airport Police Officer, Daniel Keehne works security with partner Axa Tuesday April 16, 2013 at the airport in Los Angeles. Security measures have been increased in light of Monday's bombings at the Boston Marathon.
Nick Ut
Investigators inspect the area between the two blast sites near the Boston Marathon finish line, Thursday, April 18, 2013, in Boston.
Julio Cortez
People pray during the "Healing Our City: An Interfaith Service" at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013. The service is dedicated to those who were gravely wounded or killed in MondayÕs bombing near the finish line of the Boston Marathon.
Susan Walsh
Boston Marathon runner Vu Trang, of San Francisco, cries at a makeshift memorial on Boylston Street near the finish line of Monday's Boston Marathon explosions, which killed at least three and injured more than 140, in Boston, Wednesday, April 17, 2013. The bombs that blew up seconds apart near the finish line left the streets spattered with blood and glass, and gaping questions of who chose to attack at the Boston Marathon and why. (AP Photo/Charles Krupa)
Charles Krupa
Shannon Walsh, 15, places flowers on a memorial to Boston Marathon bombing victim, Martin Richard, 8, near the Richard family house in the Dorchester neighborhood of Boston, Wednesday, April 17, 2013. (AP Photo/Michael Dwyer)
Michael Dwyer
This undated photo provided by Bill Richard, shows his son, Martin Richard, in Boston. Martin Richard, 8, was among the at least three people killed in the explosions, Monday, April 15, 2013, at the finish line of the Boston Marathon.
Unknown
Boston Marathon runners Kelli Johnston, left, and Robert Wheling of Dallas, who were married yesterday, head back to a hotel near the finish line of the Boston Marathon after their flight home was canceled, Tuesday, April 16, 2013, in Boston.
Winslow Townson
A foam finger stands at a makeshift memorial on Boylston Street just near the blast site of the Boston Marathon explosions, Thursday, April 18, 2013, in Boston.
Julio Cortez
President Barack Obama meets with Boston Athletic Association volunteers after attend the "Healing Our City: An Interfaith Service" at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013. The service is dedicated to those who were gravely wounded or killed in MondayÕs bombing near the finish line of the Boston Marathon.
Susan Walsh
Jennifer Krewalk pays her respects at a makeshift memorial on Boylston Street near the finish line of Monday's Boston Marathon explosions, which killed at least three and injured more than 140, Wednesday, April 17, 2013, in Boston. (AP Photo/Matt Rourke)
Matt Rourke
This undated photo provided by Meixu Lu shows Lingzi Lu in Boston. Boston University confirmed Wednesday, April 17, 2013, that Lingzi Lu, who was studying mathematics and statistics at the school and was due to receive her graduate degree in 2015, was among the people killed in the explosions at the finish line of the Boston Marathon Monday, April 15, 2013, in Boston. (AP Photo/Meixu Lu)
Meixu Lu
This undated photo provided by the family shows Krystle Campbell. Campbell, 29, a restaurant manager from Medford, Mass., was among the people killed in the explosions at the finish line of the Boston Marathon, Monday, April 15, 2013, in Boston.
Unknown
A mourner places a note with flowers at a police barricade near the finish line of the Boston Marathon in Boston Tuesday, April 16, 2013.
Winslow Townson
Lizzie Lee of Lynnwood, Wash., pauses near the finish line of Monday's Boston Marathon explosions, which killed at least three and injured more than 140, Thursday, April 18, 2013, in Boston. Lee said she almost completed the marathon before the blasts.
Matt Rourke
President Barack Obama, accompanied by Massachusetts Gov. Deval Patrick, center, and Boston Mayor Thomas Menino, speaks to Boston Athletic Association volunteers after attending the "Healing Our City: An Interfaith Service" at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013. Menino wear a protective boot after breaking a toe.
Susan Walsh
A memorial to Boston Marathon bombing victim, 8-year old Martin Richard is seen near his house in the Dorchester neighborhood of Boston, Wednesday, April 17, 2013. (AP Photo/Michael Dwyer)
Michael Dwyer
More than 100 people gathered Tuesday night April 16, 2013 on the track at Alexander Graham Middle School in south Charlotte to run or walk one mile in honor those lost and affected by Monday's tragedies at the Boston Marathon. After a moment of silence with candles lit, adults, dogs and children started making their way on the mile, including one runner who carried an American Flag (AP Photo/, Mark Hames)
MARK HAMES
Lizzie Lee, 56, of Lynwood, Wash., who was participating in her first Boston Marathon and 11th overall, holds a candle and a flower at Boston Common during a vigil for the victims of the Boston Marathon explosions, Tuesday, April 16, 2013, one day after bombs exploded at the finish line of the Boston Marathon.
Julio Cortez
An Army National Guard member searches the bag of a woman as she entered an MBTA subway station near Boston Common, Tuesday, April 16, 2013, one day after a pair of bombs exploded at the finish line of the Boston Marathon.
Josh Reynolds
Investigators inspect the roof of the Lord & Taylor store where a surveillance camera is placed, top right, which, an official said, is crucial in the investigation of the explosions near the Boston Marathon finish line, Thursday, April 18, 2013, in Boston.
Julio Cortez
President Barack Obama speaks to Boston Athletic Association volunteers after attending the "Healing Our City: An Interfaith Service" at the Cathedral of the Holy Cross in Boston, Thursday, April 18, 2013. The service is dedicated to those who were gravely wounded or killed in MondayÕs bombing near the finish line of the Boston Marathon.
Susan Walsh
Stefan Rozemberski, of Boston, and Autumn Rouse, of Orange County, Calif, pause at a makeshift memorial near the of Monday's Boston Marathon explosions, which killed at least three and injured more than 140, in Boston, Wednesday, April 17, 2013. The bombs that blew up seconds apart near the finish line left the streets spattered with blood and glass, and gaping questions of who chose to attack at the Boston Marathon and why. (AP Photo/Charles Krupa)
Charles Krupa
Boston Bruins hockey starters, including defenseman Dennis Seidenberg (44), stand next to a ribbon projected onto the ice at TD Garden in Boston, Wednesday, April 17, 2013, during a pregame ceremony in the aftermath of Monday's Boston Marathon bombings. (AP Photo/Elise Amendola)
Elise Amendola
Bridget Wood, 18, of Boston, holds candles during a vigil the victims of the Boston Marathon explosions at Boston Common, Tuesday, April 16, 2013, one day after bombs exploded at the finish line of the Boston Marathon.
Julio Cortez
Photos of Martin Richard, 8, Lingzi Lu, a Boston University graduate student, and Krystle Campbell, 29, hang at a makeshift memorial near the finish line of Monday's Boston Marathon explosions Thursday, April 18, 2013, in Boston. The three were killed in the explosions.
Matt Rourke
A bystander takes a photo from a window as Seattle Police Dept. robots are used to remove an item from a suspicious backpack in downtown Seattle, Tuesday, April 16, 2013. The backpack was found to be harmless, but in light of Monday's explosions at the Boston Marathon, authorities in Seattle and other cities increased security patrols and heightened the level of alertness for any possible threat to public safety.
Ted S. Warren
Investigators sift through evidence on Boylston Street just up from the finish line of the Boston Marathon in Boston, Thursday, April 18, 2013.
Winslow Townson
South Korean protesters carry a wreath for the victims killed in Boston Marathon bombings during a protest near the U.S. Embassy in Seoul, South Korea Thursday, April 18, 2013. The banner reads "Boston Marathon is international sports event. If a serial terror attack is from terrorist organization or nation, there is no reason to be forgivable."
Kin Cheung
Mary-Ann Knott-Craig, of Watertown, Mass., pauses at the site of a makeshift memorial near the finish line of Monday's Boston Marathon explosions, which killed at least three and injured more than 140, in Boston, Wednesday, April 17, 2013. The bombs that blew up seconds apart near the finish line left the streets spattered with blood and glass, and gaping questions of who chose to attack at the Boston Marathon and why. (AP Photo/Charles Krupa)
Charles Krupa
A Boston Fire Department honor guard hold flags during the singing of the national anthem at TD Garden in Boston Wednesday, April 17, 2013, during a pre-game ceremony in the aftermath of Monday's Boston Marathon bombings which killed at least three people and injured over 170 others. (AP Photo/Elise Amendola)
Elise Amendola
Two men in hazardous materials suits put numbers on the shattered glass and debris as they investigate the scene at the first bombing on Boylston Street in Boston Tuesday, April 16, 2013 near the finish line of the 2013 Boston Marathon, a day after two blasts killed three and injured over 170 people.
Elise Amendola

BOSTON -- The FBI released photos and video Thursday of two suspects in the Boston Marathon bombing and asked for the public's help in identifying them, zeroing in on the two men on surveillance-camera footage less than three days after the deadly attack.

FBI agent Richard DesLauriers said the photos of the two men came from surveillance cameras near the explosion sites. One man is seen wearing a light-colored baseball cap, the other a dark cap. The man in the dark cap set down a backpack at the site of one of the blasts, DesLauriers said.

Within moments of the announcement, the FBI website crashed, perhaps because of a crush of visitors.

The images were released hours after President Barack Obama and first lady Michelle Obama attended an interfaith service at a Roman Catholic cathedral in Boston to remember the three people killed and more than 180 wounded in the twin blasts Monday at the marathon finish line.

The break in the investigation came just days after the attack that tore off limbs, shattered windows and raised the specter of another terrorist attack on U.S. soil.

The suspects are considered armed and extremely dangerous, DesLauriers said, and people who see them should not approach them.

"Do not take any action on your own," he warned.

Generally, law enforcement agencies release photos of suspects only as a last resort, when they need the public's help in identifying or capturing someone.

Releasing photos can be a mixed bag: It can tip off a suspect and deny police the element of surprise. It can also trigger an avalanche of tips, forcing police to waste valuable time chasing them down.

At the Cathedral of the Holy Cross earlier in the day, Obama declared to the people of Boston: "Your resolve is the greatest rebuke to whoever committed this heinous act." He spoke in almost mocking terms of those who commit such violence.

"We finish the race, and we do that because of who we are," the president said to applause. "And that's what the perpetrators of such senseless violence -- these small, stunted individuals who would destroy instead of build and think somehow that makes them important -- that's what they don't understand."

"We will find you," he warned those behind the attack.

Seven victims remained in critical condition. Killed were 8-year-old Martin Richard of Boston, 29-year-old restaurant manager Krystle Campbell of Medford, Mass., and Lu Lingzi, a 23-year-old Boston University graduate student from China.

Video and photos recovered in the investigation are being examined and enhanced by an FBI unit called the Operational Technologies Division, said Joe DiZinno, former director of the FBI lab in Quantico, Va.

Investigators are looking at video frame by frame -- a laborious process, though one aided by far more sophisticated facial recognition technology than is commercially available, forensic specialists said.

"When you have something that is this high-profile, they are going to use every available resource that they have," said former Miami federal prosecutor Melissa Damian Visconti.

The investigation will probably collect about a million hours of videotape from fixed security cameras and cellphones and cameras used by spectators, said Gene Grindstaff, a scientist at Intergraph Corp., a Huntsville, Ala., company that makes video analysis software used by the FBI and other law enforcement agencies.

But after years of investigating terrorist incidents and other crimes, the FBI is practiced at cataloging, categorizing and analyzing such evidence and will winnow it down dramatically, he said.

"Back in the days of 20 years ago, you were lucky if you had video and it was probably of poor quality and it took a tremendous amount of enhancement. Today you have a completely different issue," Grindstaff said.

Investigators can set the video analysis software so that it automatically searches for certain types of objects or people matching a height and weight description. The software can also spot patterns that analysts might not notice, such as a certain car that turns up in different places, Grindstaff said.

DiZinno, who ran the FBI lab from 2007 to 2010, said any retrieved bomb components such as the pressure cookers, shrapnel and pieces of timers or wire will be closely examined for fingerprints, DNA, hairs and fibers.

The bomb components would be traced by figuring out the item's maker, where each piece is typically purchased and whether the device resembles any bombs the FBI has seen in past attacks. The FBI lab keeps a detailed file on past bombings, including many overseas attacks.

"Let's say there was a timer," DiZinno said. "Was there a serial number? Who was the manufacturer? That can provide leads for investigators."

One pressure cooker maker, the Fagor Group in Spain, said that it has been contacted by U.S. investigators and that company officials are extending full cooperation. The company sells 250,000 pressure cookers a year in the U.S. and 1 million worldwide.

------

Link to FBI video: http://bit.ly/115ZcIq

------

Associated Press writers Jay Lindsay, Pat Eaton-Robb, Steve LeBlanc, Bridget Murphy, Meghan Barr, Jeff Donn and Julie Pace in Boston; Eileen Sullivan and Lara Jakes in Washington; Curt Anderson in Miami; and Marilynn Marchione in Milwaukee contributed to this report.


By DENISE LAVOIE and ADAM GELLER
Associated Press