A New York court has convicted the Honduran president's brother of drug trafficking, a verdict immediately rejected by the Central American leader while opponents called for his resignation.
Tony Hernandez was found guilty on all four counts following a trial in Manhattan that lasted almost two weeks.
President Juan Orlando Hernandez said his brother had been convicted with "testimony from confessed murderers."
"On behalf of my family, and personally, it is with great sadness that I received word of the verdict in New York," the president wrote on Twitter.
Tony Hernandez was arrested at a Miami airport in November 2018 on charges including conspiring to import cocaine into the United States, possessing machine guns and making false statements.
The former Honduran congressman, 41, is due to be sentenced on 17 January. He faces between five years and life in prison.
Following the verdict, opposition parties in Honduras called for street protests to demand that the president step down.
Manuel Zelaya, the former president of Honduras who was overthrown in a coup in 2009, tweeted that the verdict had "unmasked the drug and corruption network run by the government of Honduras."
Although he wasn't on trial himself, the court proceedings featured compromising allegations against the president.
Prosecutors said the Honduran leader took millions of dollars in bribes from drug lords including jailed Mexican kingpin Joaquin "El Chapo" Guzman.
President Hernandez, an ally of US President Donald Trump, dismissed the accusation as "absurd" and "less serious than Alice in Wonderland," in a tweet.
The Manhattan prosecutor's office filed a motion in August alleging that President Hernandez received at least $1.5m in drug money from one of the prosecution's cooperating witnesses for his first campaign, and $40,000 for the second.
He has rejected the accusations and has not been formally charged by the US judicial system.
The US government successfully argued that Tony Hernandez was a large-scale drug trafficker who worked from 2004 to 2016 with others in Colombia, Honduras and Mexico to import cocaine into the US by plane, boat and submarine.
He helped facilitate more than 200 tons of cocaine into the US. Some of it was labeled with his initials "TH," prosecutors argued.
Hernandez made millions of dollars from the trafficking and used the proceeds to influence three presidential elections, according to US attorneys.
The prosecution also said Hernandez, who served as a member of the Honduran Congress from 2014 to 2018, was involved in at least two murders of rival drug traffickers in 2011 and 2013.
Defence lawyers questioned the credibility of the witnesses, many of them former drug traffickers, some of which had been convicted of murder, but those arguments did not influence the 12 jurors who took less than two days to convict.
Hernandez's lawyer said his client would appeal.
"The legal battle continues," Omar Malone told reporters outside court.
US Drug Enforcement Administration (DEA) special agent Wendy Woolcock welcomed the verdict, adding in a statement that the DEA and its partners would hunt traffickers "regardless of social status."
US prosecutors have aggressively pursued current or former Honduran public officials and their relatives over drug trafficking allegations.
The verdict comes after Guzman, the 62-year-old former co-leader of Mexico's feared Sinaloa drug cartel, was convicted in New York in February of smuggling hundreds of tons of cocaine, heroin, methamphetamines and marijuana into the United States.
He has been jailed for life, a sentence he is appealing.