Federal agents in the US have revealed how the Boston Marathon bombing was carried out, using kitchen pressure cookers packed with explosives, nails and other lethal shrapnel. However they insist they still don't know who did it and why.
Leaked pictures today show the mangled pressure cooker, a torn black bag, a circuit board and a battery connected to wires, all of which the FBI said were from the two bombs used in the attack.
Investigators believe the bombs were hidden in black nylon backpacks and housed inside the sealable metal pots called pressure cookers. Pressure cooker bombs can help boost the power of relatively small devices by briefly constraining the blast. And when the cookers do explode, they can add large chunks of metal to the shrapnel spray.
8-year-old Martin Richard and 29-year-old Krystle Campbell died in the twin blasts
Around a dozen of the 108 Irish runners who took part in this week's Boston marathon returned home today. Speaking to our reporter Louise Kelly at Dublin Airport these Irish runners said they were still in shock.
Mary O'Meara from Malahide in Dublin was waiting for her husband Paul to return home.
Memorial service takes place tomorrow
These details come as President Obama has confirmed that he plans to travel to Boston tomorrow, for a memorial service for the Boston Marathon victims.
Three people were killed in the twin blasts, including an eight year old boy, Martin Richard and 29 year old woman restaurant manager Krystle Campbell, who is said to have Irish links.
Krystle's grief stricken mother Patty spoke to reporters this morning:
More then 170 others were injured when two bombs were detonated near the finish line at the Boston Marathon on Monday.
Around a dozen of the 108 Irish runners who took part in this week's Boston marathon returned home today.
Meanwhile, an envelope containing the poison ricin and addressed to the Mississippi US Senator Roger Wicker has been intercepted in Washington.
It was detected during routine screening and did not reach the US Capitol building. It was postmarked from Memphis, Tennessee, and had no return address.
US cities have been on high alert since the Boston bombing on Monday.
