For Maria Gillespie, the memories of what she endured in a prison in Uruguay, when she was only 15 years old, are almost too much to bear. She remembers being hooded, interrogated and tortured. Eventually every tooth was wrenched out of her mouth. But she also remembers - as Amnesty International marks its 50th anniversary - how much she owes to the organisation that helped end the horror and set her free. I don't think that if I say 'thank you' it will be enough," Mrs Gillespie says of the Amnesty activists around the world who campaigned on her behalf. "I think that I do owe them my life." Amnesty was founded 12 years before she was jailed. It called for collective action on behalf of those unjustly imprisoned around the world. Maria Gillespie fell into that category after the military seized power in Uruguay in 1973, ushering in a period of severe repression. She was ... married to a trade union activist who was wanted by the authorities, and had fled the country. In his absence ... Maria was arrested. She was accused of aiding the regime's enemies, and sentenced to 75 years in prison. And so she began her solitary confinement in a windowless cell lit only by an electric bulb. She was repeatedly taken - with her head in a hood - for questioning about her husband's associates. But she knew nothing of his activities. She had no answers for her interrogators.