(Reuters) - A veterinarian from Colombia was charged with illegally smuggling narcotics into the United States by surgically implanting packets of liquid heroin into the bellies of puppies, U.S. prosecutors said on Tuesday.

Drug Enforcement Administration photo shows puppies as DEA announces an indictment charging Andres Lopez Elorez with conspiring to import and distribute heroin into the U.S. by surgically implanting these puppies with liquid heroin 12 years ago, in this image released in New York, U.S., on May 1, 2018. DEA/Handout via REUTERS

Andres Lopez Elorez was arraigned in a federal court in Brooklyn on Tuesday on an indictment of conspiring to import and distribute heroin into the United States, the U.S. Attorney’s Office for the Eastern District of New York said.

Elorez, 38, pleaded not guilty, U.S. news reports said.

His court-appointed lawyer, Mitchell Dinnerstein, said his client “doesn’t have any real connection” to the United States, the New York Times reported. Dinnerstein was not immediately available for comment.

Elorez faces up to life imprisonment if convicted, U.S. prosecutors said.

“Dogs are man’s best friend and, as the defendant is about to learn, we are drug dealers’ worst enemy,” Richard Donoghue, U.S. attorney for the Eastern District of New York, said in a statement.

Elorez is suspected of taking part in a conspiracy to bring drugs into the country more than a decade ago, prosecutors said.

The puppies, mostly purebred dogs including Labrador retrievers, had their bellies cut open and heroin stitched in. They were then exported to the United States with the smugglers hoping the dogs’ pedigrees would help ease their path through customs, the U.S. Drug Enforcement Administration has said.

A 2005 raid in Colombia found 10 dogs to be used as drug couriers who were rescued, but many puppies died in the operation, it said.

Elorez was arrested in Spain and extradited to the United States, prosecutors said.

“He betrayed a veterinarian’s pledge to prevent animal suffering when he used his surgical skills in a cruel scheme to smuggle heroin in the abdomens of puppies,” Donoghue said.