Boston Marathon Bombings: 1 Year Later

Members of the Boston Police Department practice marching prior to a wreath laying ceremony to commemorate the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014. (Photo by Andrew Burton/Getty Images)

Boston Marathon Bombings: 1 Year Later

Members of the Boston Police Department, Boston Fire Department, and Massachusetts State Police practice marching prior to a wreath laying ceremony to commemorate the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014. (Photo by Andrew Burton/Getty Images)

Boston Marathon Bombings: 1 Year Later

A runner speaks to Boston police officers at the finish line of the Boston Marathon on the morning of the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014. (Photo by Andrew Burton/Getty Images)

Boston Marathon Bombings: 1 Year Later

A Boston police officer waves traffic across the finish line of the Boston Marathon on the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014. (Photo by Andrew Burton/Getty Images)

Boston Marathon Bombings: 1 Year Later

A runner runs underneath the Boston Marathon finish line photo bridge on the morning of the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014. (Photo by Andrew Burton/Getty Images)

Boston Marathon Bombings: 1 Year Later

Members of the Boston Police Department, Boston Fire Department, and Massachusetts State Police practice marching prior to a wreath laying ceremony to commemorate the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014. (Photo by Andrew Burton/Getty Images)

Boston Marathon Bombings: 1 Year Later

Members of the Boston Police Department, Boston Fire Department, and Massachusetts State Police practice marching prior to a wreath laying ceremony to commemorate the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014. (Photo by Andrew Burton/Getty Images)

Boston Marathon Bombings: 1 Year Later

Massachusetts Governor Deval Patrick walks with his wife, Diane, and members of the victims families during a wreath-laying ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

Massachusetts Governor Deval Patrick walks with members of the victims families during a wreath-laying ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

Massachusetts Governor Deval Patrick shakes hands with Cardinal Sean Patrick O'Malley during a wreath-laying ceremony with members of the victims families commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

Boston Mayor Marty Walsh participates in a wreath-laying ceremony with members of the victims families commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

Boston Mayor Marty Walsh participates in a wreath-laying ceremony with members of the victims families commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

Massachusetts Governor Deval Patrick and Cardinal Sean Patrick O'Malley greet members of the victims families during a wreath-laying ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

The family of Martin Richard including Bill Richard, along with Boston mayor Marty Walsh, Massachusetts Governor Deval Patrick, and other members of the victims families stand during a wreath-laying ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

Massachusetts state and local police and fire department members present flags during a wreath-laying ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

Massachusetts state and local police and fire department members present flags during a wreath-laying ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

Massachusetts state and local police and fire department members present flags during a wreath-laying ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

Massachusetts state and local police and fire department members stand near the site of one of the bombs following a wreath-laying ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014. (Photo by Jared Wickerham/Getty Images)

Boston Marathon Bombings: 1 Year Later

Police officers carry flags during a wreath laying ceremony on the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014. (Photo by Andrew Burton/Getty Images)

Boston Marathon Bombings: 1 Year Later

Melissa Howard, from Wakefield, Massachusetts, pauses during a wreath laying ceremony on the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014. (Photo by Andrew Burton/Getty Images)

Boston Marathon Bombings: 1 Year Later

(L-R) Denise Richard, Bill Richard, Jane Richard and Henry Richard, the family of Martin Richard, an eight-year-old boy killed from a bomb at the Boston marathon, attend a wreath laying ceremony on the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014. (Photo by Andrew Burton/Getty Images)

Boston Marathon Bombings: 1 Year Later

A woman cries during a wreath laying ceremony on the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014 in Boston, Massachusetts. (Photo by Andrew Burton/Getty Images)