The cousins of Salman Abedi have spoken of how their relative was a "bubbly person" who always acted normally.
Abz Forjani, 21, and his brother Isaac, 24, who were arrested the day after the attack before being released with no charge, say they have not been able to stop crying over the slaughter of 22 innocent people at the Manchester Arena on 23 May.
"I believe it was all done by one man, (who) developed some sort of thoughts in the past few years which he kept to himself, secretly to himself.
"He never shared it with any members of the family - if he would of, we could have done something to stop that happening."
In a separate interview, he told ITV News: "He didn't have a special character, he was just a bubbly person that always acted normal.
"He never came and spoke to me about something serious. If he had, maybe I could have done something about it. If I could deny he was my cousin I would," Abz Forjani added.
Greater Manchester Police have issued more images of the bomber and have urged anyone who saw him in the Rusholme area of the city to get in touch. Police want to find out if he bought parts of the bomb he used before or after he left the country on 15 April.
Isaac Forjani told ITV News that he "couldn't stop crying" after the attack.
"And every time that story was brought up, little girls, innocent lives. You just couldn't just stop yourself from crying, that's all you can do. Their lives, 22 lives, have gone," he said.
The brothers' younger sibling Alharth, 19, is still in custody.