Paraguay's former army chief Gen Lino Oviedo has been arrested at Asuncion airport after returning from five years of exile in Brazil.
Gen Oviedo says he wants to clear his name
Gen Oviedo was taken under tight security to the Vinas Cue military prison on the outskirts of the capital.
He fled the country in 1999 after being accused of involvement in the assassination of Vice-President Luis Maria Argana.
He also faces a 10-year jail sentence for leading a failed coup in 1996.
Supporters of the former military commander staged another unsuccessful coup in 2000, but the general denied involvement in the uprising.
He was arrested on the orders of President Nicanor Duarte Frutos, the AFP news agency reported.
The former army chief insists that he is the victim of a political conspiracy and had said he wanted to return to clear his name.
He had given notice of his intention to return by plane from the southern Brazilian town of Foz do Iguacu on Tuesday in the knowledge that he would be arrested when he arrived.
"I will take a crucifix, a pencil and a small notebook," he said. "They have always helped me."
Gen Oviedo initially rose to prominence in Paraguay in February 1989, when he played a prominent part in the uprising that overthrew the regime of Gen Alfredo Stroessner and set the country on the path back to civilian government.
In recent years, he has sought to further his political ambitions, first within the governing Colorado Party and then as head of his own Unace (National Union of Ethical Citizens) political movement.
Earlier this month, the general told a Brazilian newspaper that he wanted to regain his political rights with the aim of running for the Paraguayan presidency in 2008.