The father of London bomber Hasib Hussain has said he could not believe his son was capable of the attack.
CCTV images showed Hussain and his friends carrying backpacks
Mahmood Hussain was confronted as part of BBC One's Real Story by Gous Ali, whose girlfriend Neetu Jain was killed when Hussain blew up the number 30 bus.
Speaking outside his home in Leeds, Mr Hussain said to Mr Ali: "No-one has shown me any evidence that he did it."
He said his family had not known of any plot, adding: "If I knew he could do such a thing, I would break his legs."
Some 52 people were killed when four bombs were detonated on three London Tube trains and a bus on 7 July last year.
Hasib Hussain, 19, was held responsible for the bus blast in Tavistock Square, which killed 13 people.
'In the dark'
Mr Ali requested a meeting with Mahmood Hussain but received no reply.
So he decided instead to go directly to the Hussain family home in the Beeston area of Leeds - accompanied by a BBC researcher.
Although initially reluctant to speak, Mr Hussain told Mr Ali he believed that his son had gone to London to visit his friends on 6 July last year.
He maintained that he did not believe his son was responsible for the atrocity, and said no-one in the family had any idea of a suicide bomb plot.
He said the family did not understand what had happened, saying: "We are in the dark, looking for answers."
Public inquiry plea
Mr Hussain revealed that the other three suicide bombers had come to his house, and described them as well-behaved people.
He said the media had claimed his son's friends were fanatics, but that to him they seemed like ordinary people.
Neetu Jain had phoned her boyfriend just before the explosion
Mr Hussain said there should be a public inquiry so people could see any evidence against his son.
Mr Ali, who went to Leeds to try to understand why his girlfriend was killed, said he believed that Hasib Hussain's family knew nothing about what the teenager had planned.
He said Mr Hussain was in "serious denial", but they had related to each other because of the "loss, grief, pain, anxiety, worry and fear" they had both suffered.
"By the look on his face today, I could see sheer agony and pain - the same which I suffer. I think he could see that too."
Describing Mr Hussain as "bewildered and confused", he said there was no reason to hate the Hussain family because their lives too had been "ripped to shreds".
But he added: "I can't really feel sorry for [Mahmood Hussain], for his son, because I think his son is a murderer and that will never ever go away."
Real Story: Terror on the Number 30 Bus will be shown on BBC One on Friday 7 July at 1930 BST.