Kate McCann, whose daughter Madeleine was abducted in Portugal in 2007, says she has not been put off competing in the London marathon by the Boston bombings.
She is an ambassador of the Missing People charity and is aiming to raise £20,000 to mark its 20th anniversary.
"This sickening act is just incomprehensible and the loss of life, especially that of a young child, heart-breaking.
"But I feel strongly that you can't live in fear or you don't have a life."
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Over 15,000 people were expected to turn out for the Vaisakhi festival celebrations in Leicester today.
Most areas will be mainly dry with prolonged clear spells developing, leading to patchy frost in some places
Dry and largely clear overnight, with frost developing in some areas.