"We just want to help, and all funds we receive will be used to provide direct, practical support to those affected by their service to our country."
3 men arrested in connection to slaying
There's been no indication that Rigby knew the men who attacked him with meat cleavers Wednesday afternoon.
One of the two, who approached a man filming the gory scene in the Woolwich neighborhood, suggested that Rigby had been targeted only "because Muslims are dying daily" at the hands of British troops like him. Britain's armed forces have served in Iraq and Afghanistan. All its combat troops are due to leave Afghanistan by the end of 2014.
"We must fight them as they fight us. An eye for an eye and a tooth for a tooth," he said in the video aired by CNN affiliate ITN.
Friends, acquaintances and British media have identified that man as 28-year-old Michael Adebolajo, a British national of Nigerian descent.
Police have not released his name, nor those of the others they've arrested.
Adebolajo and the 22-year-old suspect also tied directly to the attack are now hospitalized under guard after a confrontation with police in which they were shot. A 29-year-old man arrested Thursday is being on suspicion of conspiracy to murder.
Two women arrested Thursday, ages 29 and 31, have been released without being charged, police said Friday.
Police continue to search five addresses in London and one in Lincolnshire, which is in eastern England.
Suspect knew British Muslim radical leader
It is understood the two people suspected of carrying out the knife attack were known to Britain's domestic security service. They had been featured in previous investigations into other people, but were not themselves under surveillance.
Abu Baraa blamed Wednesday's attack not on his friend Michael Adebolajo -- who he says is the bloody, cleaver-wielding man shown talking in the ITN video -- but on the British government and said there may be more attacks.
"As long as (British) foreign policy is engaging in violence, they're only inviting violence in retaliation," Baraa told CNN.
By sharp contrast, Prime Minister David Cameron said "the fault lies solely with sickening individuals who carried out this attack," adding that "nothing in Islam ... justifies this truly dreadful act."
British Muslim radical leader Anjem Choudary told CNN on Thursday that he knew Adebolajo, noting the suspect attended demonstrations and a few lectures organized by Choudary's group Al-Muhajiroun.
In fact, an ITN video from April 2007 shows Adebolajo standing behind Choudary at a rally protesting the arrest of men who allegedly made inflammatory speeches inside a mosque.
Syrian cleric Omar Bakri Mohammed, who founded Al-Muhajiroun in the late 1990s, told CNN Terrorism Analyst Paul Cruickshank by phone from Tripoli, Lebanon, he also had been acquainted with Adebolajo.
Bakri Mohammed used to live in the United Kingdom but was barred from returning after the 2005 terror attacks.
Bakri Mohammed said Adebolajo, who he knew by his Muslim name "Mujahid," attended several talks he gave in London from 2003 to 2004 and was at his side at a number of Al-Muhajiroun protests against the war in Iraq around that time.