A veterinarian has pleaded not guilty to surgically implanting packets of liquid heroin into puppies to be sent to the United States.
Andres Lopez Elorza appeared in a New York court Tuesday after being extradited from Spain. He was ordered held without bail.
If convicted on conspiracy charges, he risks spending at least 10 years and potentially life behind bars.
Prosecutors said Lopez Elorza stitched packets of heroin into the bellies of Labrador retrievers and other breeds sent on commercial flights to New York City. They said the packets were then cut out of the puppies, who died in the process.
"As alleged in the indictment, Elorza is not only a drug trafficker, he also betrayed a veterinarian's pledge to prevent animal suffering," said Richard Donoghue, the U.S. attorney based in Brooklyn.
"Dogs are man's best friend and as the defendant is about to learn, we are drug dealers' worst enemy."
The U.S. Drug Enforcement Administration said 10 puppies were found on a Colombian farm during a raid in 2005. Three of the dogs later died as a result of infections.
Lopez Elorza had been on the run since.
U.S. officials said Lopez Elorza was part of a Colombian-based conspiracy from September 2004 to January 2005 that smuggled heroin into the United States using various methods to conceal the narcotics from detection.