A key witness testifying in a landmark human rights case in Argentina has appeared in Buenos Aires live and well, after being missing for three days.
Mr Gerez said he had been arrested and given electric shocks
Luiz Gerez re-appeared just minutes after President Nestor Kirchner called for his safe return on national TV.
He had implicated a former police chief in the human rights abuses committed by the 1976-83 military regime, helping block his bid for a seat in Congress.
Another witness who disappeared in September is still missing.
The BBC's Daniel Schweimler in Buenos Aires says news of Mr Gerez's disappearance struck fear into Argentine society with many believing he had been kidnapped, possibly by former policemen.
Mr Gerez appeared shortly after President Nestor Kirchner made a televised appeal, accusing what he called paramilitary elements of trying to intimidate and extort Argentine society through fear.
An estimated 30,000 people were killed, or "disappeared" during the military's repression of alleged left-wing opponents, which came to be known as the "dirty war".
Mr Gerez told a congressional investigation this year that a former police chief, Luis Patti, had been involved in torturing him.
Mr Gerez said he had been arrested and given electric shocks. He was reportedly blindfolded at the time but said he could identify Mr Patti by his voice as one of the men who tortured him.
Mr Patti had been elected to congress but Mr Gerez's testimony helped prevent him from taking his seat.
The first civilian governments after military rule passed laws which allowed Dirty War suspects to walk free.
The current series of trials began after the Argentine Supreme Court last year ruled those laws to be unconstitutional.
Julio Lopez vanished in September, after giving evidence at the trial of another former police chief accused of human rights abuses during the same period.