Alexis Arguello, who fought in one of boxing's most classic brawls and reigned supreme at 130 pounds, was found dead at his home early Wednesday.
Presidential spokeswoman Rosario Murillo confirmed Arguello's death and an autopsy was pending. The La Prensa newspaper reported Arguello — elected mayor of Managua last year — was found with a gunshot wound to the chest.
The 57-year-old Arguello retired in 1995 with a record of 82-8 with 65 knockouts and was a champion in three weight divisions. He was perhaps best known for two thrilling battles with Aaron Pryor and fights with Ray Mancini, Bobby Chacon and Ruben Olivares.
"I'm kind of in a daze right now," Pryor told The Associated Press. "Those were great fights we had. This was a great champion."
Nicknamed "The Explosive Thin Man," Arguello was inducted into the International Boxing Hall of Fame in 1992, where flags were flying at half-staff in his honor Wednesday.
In 1999, a panel of experts assembled by The Associated Press voted Arguello the best junior lightweight and sixth-best lightweight of the 20th century. Arguello never lost a fight at 130 pounds.
His popularity in his own country was so great that he carried the flag for Nicaragua at the 2008 Beijing Olympics, and led to his decision to seek public office.
Arguello turned professional in 1968 and promptly lost his first bout. He didn't lose much after that, and six years later rallied to knock out Olivares in the 13th round and win the WBA featherweight title.
Arguello went on to win the super featherweight and lightweight titles, his 5-foot-10 frame and long reach allowing him to move up in weight without losing his tremendous punching power. At the time, he was only the sixth boxer to win championships in three weight classes, and was considered for a while the best pound-for-pound fighter in the world.
Arguello moved up in weight again in November 1982 to challenge junior welterweight king Pryor in a fight billed as "Battle of the Champions," attempting to become the first fighter to win titles in four divisions. More than 23,000 fans packed the Orange Bowl in Miami, and the two waged an epic battle in which Pryor knocked out Arguello in the 14th round.
The bout was named "Fight of the Year" and "Fight of the Decade" by Ring Magazine, but was shrouded by controversy. Pryor's trainer, Panama Lewis, gave him a water bottle after the 13th round that many believe contained an illegal substance — an accusation Pryor denied.
A rematch was ordered and they met again a year later at Caesars Palace in Las Vegas. This time, Pryor knocked out Arguello in the 10th round.
He announced after the fight that he would retire from boxing, but as so often happens in the sport, Arguello couldn't stay away from the ring.
He returned in 1985 to beat Pat Jefferson, and won another fight the following year, but didn't step into the ring again until 1994. After defeating an unknown club fighter in Miami, Arguello lost to journeyman Scott Walker in January 1995 and retired for the last time.
"Alexis Arguello was a first-class fighter and a first-class gentleman," said Hall of Fame executive director Edward Brophy. "The Hall of Fame joins the boxing community in mourning the loss of a great champion and friend."
Arguello fought against the Sandinista government in the 1980s after it seized his property and bank account, but later joined the party and ran for mayor of the capital last November. He defeated Eduardo Montealegre, though opponents alleged the vote was fraudulent.
Arguello had returned Sunday from Puerto Rico, where he honored the late baseball Hall of Famer Roberto Clemente. His death prompted Nicaragua President Daniel Ortega to announce he was canceling a trip to Panama for the inauguration of President-elect Ricardo Martinelli.
"We are upset," said Murillo, whose office declined to provide details about Arguello's death. "This is a heartbreaking announcement. He was the champion of the poor, an example of forgiveness and reconciliation."