Two Muslim brothers, Dzhokhar Tsarnaev and Tamerlan Tsarnaev were identified as suspects but escaped initial capture. The brothers were later confronted during a massive manhunt operation. Tamerlan Tsarnaev died after a shootout with authorities that also resulted in the death of a police officer, Sean Collier. Dzhokhar Tsarnaev was later found in a boat parked on a driveway in nearby Watertown, Boston. He was arrested, went to trial and on April 15, 2013 receives the death sentence.

When was Boston Marathon bombing? Boston Marathon bombing took place on April 15, 2013.

How many people died in Boston Marathon bombing? The death toll of  Boston Marathon bombing numbered 3 innocent civilians, Krystle Campbell, Lu Lingzi and Martin Richard, and more than 280 people were injured in the terror attack

Who was arrested for the Boston Marathon bombing? Dzhokhar Tsarnaev was arrested for the Boston Marathon bombing and sentenced to death on April 15, 2013. His brother and co-conspirator Tamerlan Tsarnaev was shot dead in the shoot out during the manhunt for the perpetrators. 

Who was responsible for the Boston Marathon bombing? The Muslim brothers were radicalized by their beliefs in the Islamic State (IS).

Facts about Boston Marathon bombing
The following fact sheet contains interesting facts and information on Boston Marathon bombing.

The Boston Marathon has a long history and dates back to 1897 when the first marathon was run. It is New England's most widely viewed sporting event

More than 30,000 athletes are inspired to run the race each year, many for charity, along the course of winding roads covering 26 miles, 385 yards conforming to the Olympic standard. The annual event attracts over 500,000 spectators.

The 2013 Boston Marathon was greeted with the usual enthusiasm. It ended in tragedy when the event was subjected to a terror attack perpetrated by two young men, Tamerlan Tsarnaev and Dzhokhar Tsarnaev, who had lived in the United States throughout their adult lives.

Tamerlan Tsarnaev and Dzhokhar Tsarnaev came to the U.S. from Kyrgyzstan, a Central Asian state bordering Uzbekistan, when they were aged 15 and 8, respectively. The family originated in war-torn Chechnya.

The Tsarnaev family reached the United States on tourist visas and applied for asylum. The family settled in Cambridge, Massachusetts and granted legal permanent residence in 2007.

The older brother, Tamerlan, attended Bunker Hill Community College, was a keen boxer and had hopes of representing the USA in the Olympics. He dated American girls and appeared settled.

In 2008 his lifestyle changed. He became a devout Muslim, attending the Islamic Society of Boston mosque. Tamerlan Tsarnaev became radicalized and stated expressing extremist views against the west. In 2011 the FBI received warning information that Tamerlan Tsarnaev was a follower of radical Islam.

In September 2011 Dzhokhar Tsarnaev enrolled in the University of Massachusetts Dartmouth and was popular among his fellow students, but was strongly influenced by his older brother.

From January 2012 until July 2012 Tamerlan was in in Russia, in the predominantly Muslim provinces of Dagestan and Chechnya. He retuned to the US and began to loudly express his extreme radical views at the mosque.

It later transpired that in 2013 Tamerlan downloaded a publication by Abdullah Azzam advocating violence to terrorize enemies of Islam and a publication that glorified martyrdom in the service of violent jihad.

He then downloaded a copy of the "Inspire" magazine published by Al-Qaeda  which included an article, "Make a Bomb in the Kitchen of Your Mom," with instructions on how to build improvised explosive device (IEDs) using pressure cookers or sections of pipe, explosive powder from fireworks and shrapnel such as nails and ball bearings.

On April 14, 2013 Tamerlan Tsarnaev ordered electronic components over the Internet to be used in making the IEDs which he received by mail.

The 2013 Boston Marathon gan at 9.00am on April 15, 2013 and vast crowds began to gather along the route

Tamerlan Tsarnaev was aged 26 and his younger brother, Dzhokhar Tsarnaev, was aged 19 on the day of the Boston Marathon bombings.

At 2:40 p.m. Tamerlan Tsarnaev walked to the front of Marathon Sports shop on Boylston Street and placed a backpack containing a pressure cooker bomb among the crowd gathered near the finish line.

At about the same time Dzhokhar walked to the front of the Forum restaurant, about a block and a half away from Boylston Street, and let a second backpack and pressure cooker bomb among the crowd.

Tamerlan Tsarnaev detonated the bomb in front of Marathon Sports at 2.49p.m., killing 29 year old Krystle Marie Campbell and maiming many others.

Seconds later Dzhokhar detonates the second bomb in front of the Forum restaurant, killing 23 year old Lingzi Lu and eight year old Martin Richard, burning and maiming many others.

The homemade pressure cooker bombs, packed with explosives and shrapnel, were triggered remotely, by a device used in remote control toys, allowing the bombers to escape. They immediately return to their day to day routines.

The manhunt for the bombers began. Jeff Bauman, who lost both legs in the bombing, bravely gave the FBI a description of the man who dropped a backpack near him.

On April 17, 2013: President Barack Obama signed an emergency declaration for Massachusetts and ordered federal aid to supplement local response units.

On April 18, 2013 investigators released photos and a video of the two suspects and requested the public's help in identifying them. Dzhokhar Tsarnaev and Tamerlan Tsarnaev were identified as the suspects

The manhunt increased in intensity, and Boston was effectively locked down. The brothers, aware they had been identified, were looking for more weapons to defend themselves.

On the same night, MIT police officer Sean Collier was on duty in his squad car when he was shot to death, allegedly by Tamerlan and Dzhokhar Tsarnaev, as they attempted to steal his gun.

They then stole a Mercedes SUV at gunpoint from a Cambridge gas station. The driver was held for about a half-hour, then released unharmed.

In the early hours of 12:15 a.m., on April 19, 2013, the brothers drive to Laurel Street and Dexter Avenue in Watertown, where police try to apprehend them

A gun battle begins and Tamerlan Tsarnaev, weakened by multiple gunshot wounds, is tackled by three Watertown police officers, Jeffrey Pugliese, John MacLellan and John Reynolds.

Dzhokhar Tsarnaev, also bleeding from multiple gunshot wounds, flees to the Mercedes SUV and steers it directly at the three police officers, but the car hits his brother.

Tamerlan was taken to Beth Israel Deaconess Medical Center and pronounced dead at 1:35 a.m.

Dzhokhar abandons the Mercedes on Spruce Street in Watertown and hides in a dry-docked boat called 'The Slipaway II', in a backyard in Watertown.

At 8:30 p.m. the police corner Dzhokhar in the boat. They order him to come out with his hands up and he gave himself up. He is taken to hospital and later questioned by the police.

On May 9, 2013 the body of Tamerlan Tsarnaev is secretly buried in Virginia after a weeklong search for a cemetery willing to take the body.

On April 8, 2015 Dzhokhar Tsarnaev was found guilty of carrying out the 2013 Boston marathon bombing and receives the death sentence.

Whilst the death penalty is not permitted under state law in Massachusetts, it was an option in the Tsarnaev case because he was convicted of federal crimes.

Dzhokhar Tsarnaev is incarcerated in Supermax, the country's most strict and secure prison, in Florence, Colorado, pending appeal.