Police arrested Former Salvadoran President Tony Saca for alleged illicit enrichment, unlawful association and money laundering on Saturday, prosecutors said.
Police said six former officials in his government were also arrested. Saca and two of the other suspects were arrested at the wedding of one of Saca's children.
Saca, a former radio sports announcer, held office from 2004 to 2009 for the rightist Nationalist Republican Alliance.
Prosecutors say the former president has not clarified the origins of $5 million of the $6.5 million in assets he acquired during his time in office.
He declared his fortune at $3.6 million when he took office. Five years later, it had grown to $13.1 million.
But newly surfaced evidence suggests the sums involved could be even larger.
Elmer Charlaix, Saca's former private secretary and one of those arrested, allegedly had $5.8 million in private bank accounts and prosecutors said he could not explain the origin of the money. He allegedly wrote about $15 million in checks to Saca, other officials and Saca's party.
Charlaix turned himself in at a police station, saying: "I have come to face the accusations against me."
Former President Mauricio Funes, who succeeded Saca, is also under investigation for alleged corruption. Funes, who governed From 2009 to 2014, has taken asylum in Nicaragua.
Another former president, Francisco Flores, died of a cerebral hemorrhage last January while awaiting trial for allegedly diverting millions of dollars in earthquake aid to his political party.